Transmission crossmember bolt size

I am in the process of pulling the 4L60E transmission from my 2003 4wd Silverado, and before I go to the store to buy a bunch of different size sockets, I was wondering if anybody on here knows what size the crossmember bolts are?

Either 15mm or 18mm, but either one will be in the 8mm-19mm set of sockets you buy. You don’t buy sockets one by one.

The biggest I have is 19mm and it’s too small. If I wasn’t clear enough, it’s the bolts connecting the crossmember to the chassis. I’m thinking maybe 21mm.

I don’t remember them being that big but I can’t remember anything anymore. I think the bolts that hold the transmission to the crossmember are 15mm. If you have standard tools 21mm is about 13/16 and 22 is about 7/8 if that helps.

I did it last week. Vertical bolts are 15mm. The 4 horizontal bolts are 18mm

Put a crescent wrench on the bolt, then take it with you to the store.

I suggest that you simply go out and buy a full metric socket set. If you’re going to be doing your own work, it’ll be an invaluable investment. And check the set to be sure all the sizes are included. For some odd reason, many sets seem to have one or two sizes not included, often a 16mm. It’s worth the extra money to get a complete set.

If you’d like suggestions on other tools to get for your tool chest, post back. There are things like ratcheting box-end wrenches and deep sockets that you might not need regularly but sure are great to have when you need them.

I agree with the same mountain bike. If you’re doing transmission removal work be sure to get 1/2" drive. The fact that your largest socket is 19mm suggests that you may have a 3/8" drive set.

I prefer the Japanese method of fasteners. With wrench sizes they generally use 8 MM, 10 MM, 12 MM, 14 MM, 17 MM, and 19 MM on just about everything.
None of that oddball 15, 16, 18, and 7 MM or German Triple Square BS.