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1975 Blazer Hi Loc

Hi, I just bought a 1975 Jimmy to plow my driveway. Yesterday I got it stuck and I noticed that in both Hi Loc and Lo Lock only the passenger side wheels were turning. Is this normal? I thought all 4 wheels would turn in those settings. It has automatic hubs if that helps figure it out. Any advice would be appreciated.

If has an open front diff (and most 4x4’s do) then if one wheel loses traction, then all the power will be sent to the wheel without traction and it’ll just spin. 4 Hi and 4 Lo just refer to the gear reduction in the transfer case. 4 Hi has no reduction (like normal 2WD operation) and 4 Lo gets you some gear reduction (typically around 1.90-ish :1 to around 3.5:1 or 4:1 for something really off-road oriented like a Wrangler Rubicon.)

Thanks for the information but what I’m wondering about is hi loc and lo loc. The shifter has lo loc, low, neutral, high & hi loc. I understand that it’ll do what you said in regular hi and low but I thought the loc position would make all 4 wheels turn. I guess my question is am I wrong or is something not working right? Also I just check the VIN and its actually a blazer. Not sure if that makes a difference.

No, the ranges only apply to the transfer case, it does not lock your differentials. Chances are, on a ‘75 the rear differential is an open diff too. In ‘75 a limited slip diff was optional.

So, one more dumb question please…what’s the advantage of hi loc over hi? Thanks.

In High it operates like a 2X4 truck, front drive shaft is not engaged. 4 high engages the front driveshaft.

Your transfer case has a differential inside it to allow you to use 4 Hi as a full time 4wd. 4 Hi Loc, locks the transfer case differential for a little better traction (otherwise only ONE wheel would spin) but you should only use 4 Hi Loc on slippery surfaces.

It should have a New Process 203 transfer case.

That style transfer case is really an AWD (all wheel drive) transfer case
Loc locks it into 4WD (four wheel drive) Hi or Low depending on where you move the selector to.

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I learned something, did not know about the NP 203, nor that it had a center differential.

Awesome, thanks for the help everyone. I’m using it just for a plow truck in my driveway. It’s 1/2 mile long and usually covered in ice and snow this time of year. (I’m in Quebec Canada) So hi loc seems like a good plan.

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In some years during mid-70’s you could get full time 4WD (basically AWD) or a traditional part time system in GMC/Chevrolet half ton trucks/SUVs. I want to say that AMC/Eagle offered full time 4WD around the same time period as well. 30-40 years later history is repeating itself, with the glut of AWD options we currently have on the market.

Back then I had a IH Scout, then a CJ5, they both had the old shift on the floor transfer case and manual hubs.