I might suggest that you add an aftermarket transmission fluid cooler and do completely away with the cooler in the radiator. AM fluid coolers are cheap, easy to install, and worth their weight in gold.
Combine that with regular 30k miles transmission service intervals and the transmission will probably outlast you and all of us.
Here’s some more information. Hopefully this well help
@db4690, i went out and found the GCVWR on the panel of my driver’s side door. It said: 6600. Yes, i was thinking along the lines of, at most, the equivalent of maybe a 6x12 uhaul cargo trailer, which is stated to have an empty weight of about 1920 lbs. And, in terms of a popup camper, at most, the ones that are stated to be 1600-1700 lbs.
And thanks for your addition, @asemaster. Yes, that is weird. Bcz my VIN does include the “2” as the sixth character, which, according to my manual, means that it is 3/4 ton. i’ll have a formal weighing done when i finally choose a shop so that i can make a confirmation.
the first eleven characters of my vin ar: 2GBEG25K3N4 (yeah, yeah, i know–canadian built haha 
)
Thank you, @ok4450. great advice! i’ll add that to my list! 
WOW! thank you so much for the link, @db4690!
yes, @asemaster, the file that @db4690 sent me the link to states that the Front Brakes Rotor Size is the same in terms of diameter x thickness (in.) for the 1992 G10 and 1992 G20: 11.86 x 1.29
Yes, that is weird. Bcz my VIN does include the “2” as the sixth character, which, according to my manual, means that it is 3/4 ton. i’ll have a formal weighing done when i finally choose a shop so that i can make a confirmation.
The “3/4 ton” designation has nothing to do with how much the van weighs. It refers to an outdated measure of load capacity.
“The “3/4 ton” designation has nothing to do with how much the van weighs. It refers to an outdated measure of load capacity.”
It also has very little to do with the mechanical construction of the van. It just means that the van when loaded to capacity it is rated as a 3/4 ton vehicle, often subject to higher tax rates and less stringent safety and emissions standards.
Mechanically speaking there is little or no difference between the engine, transmission, brakes, steering, suspension, and rear axle in the G10 and G20 series.
Well I guess that is why my daughter is on her third Jasper engine and it still doesn’t run right.
I have had good luck with aftermarket Taiwan radiators. And also aftermarket parts from Taiwan. They are really high quality.
Oh, okay, @NYBo and @asemaster. Thanks. Yes, I’ve been reading now about the difference between “payload”, “GVWR” and “GAWR”. According to the file that @db4690 gave me, for my van those (standard) are 2060, 6600, and 3400front/3400rear, respectively. But, on the sticker on the door panel of my van it says GVWR:6600, GAWR-Front:3400, and GAWR-Rear:3406
I hate that for you and your daughter, @oldtimer 11. (about Jasper engines, that is.) I’ll put a new engine in my van eventually. But I want to try to get as many GM parts as possible, unless my research and the advice i get here points me in other directions. I sure appreciate all of you. And, thanks for the info about the radiators, @umair.
So, my sister works at a chevy dealership in bryant, arkansas as an accounts rep. I asked her to see if she could get me a quote on a new or rebuilt GM 4L60. The Parts Manager told her that all he could get me was a rebuilt one, not new. But it has a 3YR/100,000mi warranty 
The price: $1,386+tax (includes a core charge). Unfortunately, he wouldn’t answer my question of whether or not it was a 4L60 or a 700R4? And simply maintained that “it’s the same thing”. But, again, remember when i said that i read that, although they do have many interchangeable parts, the pump and valve body are different? I want to get this van back to as “true original” as possible (of course, with improvements when possible). Any advice on this new development? I have to go to class now, so i’ll check back later tonight. Thanks everyone!
That $1386 transmission sounds pretty good to me, as long as it’s the correct unit for your van
I live near Jasper, Indiana which is the home of jasper engines. I think there was a time where they used to used to be good, but like many things they will save a nickle and sacrifice quality.
I have heard Jasper doesn’t honor their warranties with out a fight, BUT, How many of those issues were due to poor installation? Im not sure.
Jasper was owned by a rich family in Dubois county Indiana and if you try to sue them they have the legal system in their pockets, so it isn’t going to happen. Typical good 'ol boy network. Now I think they are employee owned, but im not sure.
That being said, I also heard the Jasper sells 10,000+ units a month and has a less then 1% failure rating, Good if you ask me.
okay, thanks @db4690. i’ll just have to do some more research about the true difference between a 4L60 and a 700R4.
and, thanks for your input @WheresRick. that 1% does sound good! i just don’t want to be part of it haha and your info about their fighting warranty fulfillment blows, which i’ve also read accounts of. Especially when the cost difference i was quoted (for GM rebuilt/3YR,100,000miles vs the jasper-same warranty) is about $1,084.
I think i might try going with this GM rebuilt from my sister’s contact at the bryant, ar chevy dealership (after i do some more research about the true difference between a 4L60 and a 700R4, that is). At least that will be finally my answer to this seemingly first step. then i have to find a specialty transmission shop like you guys said. that one guy at Parkway Automotive hasn’t gotten back to me yet. maybe he thinks that i will be too much trouble; or that my asking to keep all of my old parts is weird. I’ve got a few specialty shops in mind to call for a labor and tow quote. one is called Razorback Transmission. another one is called Bonds Transmission Service. both have good reviews.
When you buy a transmission, there is always a very substantial core charge, which you’ll get back when you turn in your old transmission
That said, I don’t think it makes financial sense to hang on to your old transmission after the new one’s installed
As for those transmission shops you mentioned, ask them what kind of warranty they’ll give you if you supply them with that genuine GM transmission. I assume they’ll warranty the labor. Some shops don’t like to install customer supplied parts
Does the GM transmission retain the full 3 year warranty, even if it’s not installed at a GM dealer?
The model numbers 700R4 and 4L60 are used to describe the same transmission.
In 1989 GM changed its transmission model numbers to better identify its transmissions.
The THM 700R4 became 4L60
The THM 400 became 3L80
With the revised system the first character identifies the number of forward speeds,
The second the configuation (L=Longitudinal)
The third and forth the torque capacity.
Is the dealer that your sister works for too far away to take the van for repair? It may be worth the extra expense to have the transmission repaced at that dealer to have the parts and labor warranty at one company and covered nationwide.
The 1386 at the dealer sounds very fair and I would suggest that the dealer labor charge for installing that transmission might not vary as much from an independent shop as you might think.
Having the dealer install the trans they sell could be beneficial and less hassle at some point down the road if the trans were to develop a problem while in the warranty period. The odds of the transmission developing problems are very, very slim though.
The reason why you won’t find a new, non-rebuilt transmission is because it would be considered obsolete by GM and would not have been manufactured new in quite a while.
Like the guys above said, the 700R4 was just the early model designation of the same transmission.
This is just anecdotal, I have no hard data to back this, but the early 700R4 transmissions were not particularly stout. They seemed to fail early, a friend who worked at a Chevy dealer remembers that they kept rebuilt units in stock and if it was a 2WD truck or van, often the customer could wait for 3 or so hours while he installed the replacement.
By the time they were called 4L60 they were supposedly updated and held up better. So what you want is the 4L60–a “new and improved” 700R4.
You’ll never get to keep your old part, they need it to disassemble and rebuild for the next customer.
Unless you want something like this: http://www.lsxtv.com/news/new-products/new-gm-4l60e-4l65e-4l70e-transmissions-offered-by-gearstar/
Personally, I would give the dealer the chance to do this. The warranty will be nationwide and you’re never far from a Chevy dealer.