> -Is this a TH700R4 trans?

Yep. They introduced those in about 1983.




> -When searching for another trans, what are my interchange options?

700R4 is it unless you want to do a lot of sorting-out and perhaps some
driveshaft surgery. I would venture that you can further limit it to
the less common 30-spline variant.

It also matters whether this is a 2 or a 4 wheel drive, in terms of
whether its physical size is drop-in or requires modifying or moving
something.




> -Will a 700 from a gas engine work? What about a 350 or 400?

You might be at least preferentially limited to ones out of diesels. I
gather that they're different in shift calibration and the parts that
affect it, and have different pumps and a lot of differences internal
to the torque converter.

I've never taken a close look at how the all important throttle valve
doo-whackey is implemented on diesels.

I think the 700R4 is three or four inches longer than its three speed
predecessors.

The search comes to a halt in 1993, when the 4L60E was introduced --
same size, I think, but it needs to talk to a computer.

> -He has an old 3 speed standard (floor shift) that is in a mid '70's
1 ton. Will that work?

Might fit but you probably wouldn't be doing yourself any favors in
gas mileage on the highway. You'd also have to retrofit the whole
clutch and its pedals.


Bottom line: I'd consider rebuilding the one you've got. The
diesel-type 700R4's seem, in a cursory look, to be a fair bit more
expensive than the ones for gassers, if you were to just go out and buy
one off the shelf. You might stumble upon one in a junkyard, though
it's hard to tell what condition they're in.

Cheers,
--Joe