I've searched but have found varying answers

I currently have a 12/74 '40. F motor but factory 4spd

I have an entire 3spd drivetrain from Flywheel to rear output flange

I found a SM420 locally but havent bought it yet because i'm not 100% sure of what i'm doing.

I've read i need:
3spd bellhousing and flywheel Check
Sm420
Chevy 10"-something clutch disk
Pilot bearing bushing Check
SM420 input sleave for the throwout bearing to ride on, easy enough so check
1/2 wall, 1/2 thick ring to make the 420's input retainer diameter the same as the 3spd.
3spd transfer case Check


I was under the impression that the 420's splines and the 3spd case match so all thats needed is a plate adapter which i could make.

I have read that there is a spud shaft adapter thats needed, something i can't make

So what do i need? can i make the tranny/TC adapter myself? are these adapters available anywhere? seems like all the links i find are very old and either the website doesn't exist of they say they are no longer made.

http://www.extremebends.com/mechanical-sm420-adapter-c-108_42/sm420-plate-with-install-kit-p-137

http://www.extremebends.com/bmz_cache/2/2a8427f3e431bba67a75e1886e0ef42d.image.112x120.jpg

I have a 78 2F with an SM420. From what I recall, I used the 1F bellhousing, 2F flywheel/pressure plate, 2F hydraulics. I used a 10" 10 spline Chevy clutch, new pilot bearing with adapter for the SM420, I bought an input shaft adapter for the SM420 to 2F throwout bearing, I bought an input housing ring to center the SM420 in the 1F bellhousing. Other than that, I think I used some early driveshaft flanges to clear the hump on the SM420 and to mate to my 4 speed drive shafts. Oh yeah, I had to buy a 3 speed t-case since I had the 4 speed t-case. I bought the plate adapter from Danny Warden. I do not remember what shifter I ended up using for the SM420.

I do not remember what shifter I ended up using for the SM420.

LandCruiser 3 spd stick works perfectly.

I have read that there is a spud shaft adapter thats needed, something i can't make

The spud shaft refers only to the AA 4.5" long adaptor, not the plate style. You will be able to run a pto winch w/ the AA style, not so w/ the plate.

http://www.extremebends.com/mechanical-sm420-adapter-c-108_42/sm420-plate-with-install-kit-p-137

http://www.extremebends.com/bmz_cache/2/2a8427f3e431bba67a75e1886e0ef42d.image.112x120.jpg

I hope he's started making parts again. He didn't sound optimistic apout producing parts when I talked to him a couple years ago.

check ih8mud tech links ............good info in there about this swap........i like it better than stock w/ orion personally. and a hell of a lot cheaper...... but then again i wheel alot with it

I had a stock 72 w 3spd, i used the extreme bends plate. If i remember, i needed a a pilot bushing, an index ring, a 10" chevy clutch disc, and a bolt/washer/codderpin setup for the output shaft. I clearanced the front drive flang by grinding the flange and the 420 case. now it works perfect. best mod i ever did.

however, years later, when i went for the SBC swap, i used the advanced adapters rear xfer case crossmeber. the plate clocks the xfer 5 deg. to clear the fornd drive flange, so i had to mcgeyver some shit to make it work. just one of those little things

I've been running my set up for about 12 years - works fine. The 420 is in now way a fast shifting, high speed transmission. And its really a three speed- you'll never use first on the street. But the conversion is cheap. If I did it again though, i would put an SM465 in. There is a thin plate adapter for that too these days. You should check into that conversion before you buy the 420. The made SM465's into the late 1990's.
Novak offers a rebuild kit with bearings and syncros for the 420.
When you "glue" it all together, use this sealant for a leak free assembly: http://www.permatex.com/products/Automotive/automotive_gasketing/anaerobic_gasket_makers/Permatex_Anaerobic_Flange_Sealant_a.htm

And do the locking washer trick on the t-case gear (theres a write up on Mud for this)

good luck-
Dustin

I hope he's started making parts again. He didn't sound optimistic apout producing parts when I talked to him a couple years ago.

Just bought one a few weeks ago. They were in stock then.