Vortec 7400/Muncie help

[JonathanD]

I have a line on a big block for a good price. Will the Muncie in my truck bolt up to it, and what do I need to do it? It came out of a 98 suburban. The truck is a 70 lwb rwd that currently has a 350 in it. I really want to keep the trans.

[Mike C]

I would think just getting the correct flywheel would be all that it took. 168 tooth for a 7.4l externally balanced with correct bolt pattern for your year. Everything else should be useable. You might be able to run the big block on the small block mounts which keeps the trans in same spot. You will need to build a custom z bar (crossshaft).

If you go to big block mounts, you need those for the manual trans bellhousing as well since they are moved up and to the front. They are not so common... Also need clutch pushrod from pedal and appropriate cross shaft.

[JonathanD]

Thank you. That's the first I've heard of using the small block mounts, that would make my life considerably easier. A new crossshaft should be pretty simple to fab up.

[clay68c10]

Maybe a set of square body engine stands/mounts would do the trick also. They are easier to find.

[Mike C]

The challenge with the big block swap on the manual trans is that the bellhousing mount crossmember has to move forward if you use different mounts. Because the frame curves up right there, the crossmember is a different size/shape that the bellhousing bolts to. And most of the clutch linkage pieces are different.