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I have a 1995 GMC Safari van that has a bad motor it is all wheel drive now my 70 chevy has the granny 4 speed in it so going down hill with the wind at my back I might break 60 but i would be tacking the motor past 4000 rpms so my idea in theory is to put the safari transmission into my 70 chevy I know i will have a few problems with the electronics but at least its all there so to all the stove bolters out there what do you think will this work ?

What transmission is it?? You don't even say if it's automatic or not. Is the '70 a half ton? 12 bolt rear?

The "granny" nickname only applies to first gear, 4th is 1:1. You will need an OD trans to reduce engine speed. (I'm REALLY tired of people seemingly not understanding this concept.)

4,000 RPM @ 60 is BS. You'd need something like a 6:1 rear end to do that with normal tires. What is it ACTUALLY running at?

You could have a low rear end ratio, like 4.11, 4.56, or even 5.13.

3.73's, like a lot of trucks had, give you 70MPH @ 3,000RPM. 3.08 gears would give you 70 @ 2,400.

I don't know about a 4x4 Safari Van and what trans was used, but unless it's a T-5 OD 5 speed, I'd forget it, personally. Late model auto's are a pain, expensive to repair, and IMO just do not belong in a '70 pickup.

Here's what I'd consider doing:

Get a different ring & pinion, leave the 4spd. You'll probably want the low first with a 3.08 or something.

Or, get a T-5 5 speed OD. Cheap, and pretty easy swap from what I've read. Close ratios. Was used in Ford Mustangs, Astro vans, and more.

Or, find a New Process A833 (GM MY6) OD 4 speed out of an 80-85 pickup. Comes with Hurst shifter. Direct drop in to a Sm465 I think, but hard to find. .73 OD, 2,200RPM @ 70MPH with 3.73's.

Also, what engine is in your truck? You say -"going down hill with the wind at my back"- you might make 60. If it's laboring that hard now, chances are it won't like tall gears any better.

Me and my father have been looking at this for a while to get a faster ecomnomical highway cruise out of his '66. we haven't done it yet, but the T-5 seems like the best choice so far, driveability wise. The A833 we just heard about, it's essentially a 3spd with OD, just like the "granny" SM465 is like a three speed with a super-low first. The 3.08's I don't think would be as nice for around-the-town stuff.

Hope this helps some,
Chaz

Chaz, Try and take it easy on us folks who don't know any better. Some of us (like me for instance) are just learning about old trucks.

I'm REALLY tired of high gas prices! But not of people who ask questions.

Anyway, I 'm glad to know that you know your way around a truck and are interested in helping people. I learn from reading questions asked on other posts.

Sorry, I didn't really mean for it to be directed to him, just the concept in general that keeps getting propagated that somehow a SM420 "granny" has a lower 4th than a Muncie M-20 or whatever. Doesn't show up well in computerland. I apologize if I offended anyone.

-And just be glad we don't live in the UK, it's something like $10 a US gallon there! Makes $3.30 seem like a deal. I sure do miss $1 a gallon, though.

The Safari trans is most likely a 4L60E. It won't work unless the tailshaft is swapped out for the 2wd version, plus it will require either the stock PCM or some sort of aftermarket control module.