5.3LS behind 85 4spd manual?

[68c10owner]

A friend of mine is picking up a 85 3/4 ton 4wd that is a factory 4spd manual and wants to install a 5.3 LS. Is there adaptors available so he can reuse the original 4spd transmission?

[mongocanfly]

I used Advance adapters on mine. Youll need adapter bellhousing and the clutch pressure plate flywheel setup to make it all work. Get ready...it ain't cheap to do.

[68c10owner]

Originally Posted by mongocanfly

I used Advance adapters on mine. Youll need adapter bellhousing and the clutch pressure plate flywheel setup to make it all work. Get ready...it ain't cheap to do.

I'll pass it on to him. He might decide on something else. I told him I would ask because I didnt know what was available.

[Keith Seymore]

If it is the RPO M20 SM465 4 speed it is not a "high performance/racing" transmission: it will have three forward gears and a 6.56:1 creeper low gear.

He might want something else if he is going for "sporty".

K

[68c10owner]

It's a long bed 3/4 ton 4wd. Don't believe he is going for "sporty". I think more reliable with better power is what he wants but don't think he wants to spend a lot of money on adaptors.

[slotard]

Given the same rear end, I'd expect better highway mileage with an overdrive automatic than a 465. In a 3/4 I'd go 4L80E (or a 6L80/6L90). Or an NV4500 or NV5600 if he wants to keep it stick.

[Zoomad75]

You don't have to get a complete advanced adapters setup to run the old school manual trans behind the 5.3.

Follow this link as it has a good bit of info to follow and save bucks from going with the AA stuff.

http://67-72chevytrucks.com/vboard/s...d.php?t=421258

The main issue is the thickness of the flywheel on the gen 3/4 stuff differs from the gen 1 setup. Getting the flywheel they list is a little thicker to take up the difference by making the flywheel surface in the same position as the gen 1 clutch would be in. Meaning, you use the stock bellhousing and clutch. Just make sure to get the LS2 pilot bearing.