TH350 to SM456 swap?

[adams18]

I have a 1978 1/2ton with a sb350/th350/np208 and i just recently purchased a 1976 3/4ton parts truck that has a 350/sm456/np208 because i broke something in my 208, im pretty sure it was the chain, and i hate to drive autos. i was going to just drop the th350 and 208 out of my pickup and put the sm456 and 208 from the parts pickup under mine..probably easier said than done. im not too sure what going from an auto to a manual takes or what parts i need for my pickup to have the sm456 setup work right. Has anybody done this before or have any ideas about it? Thanks

[VileZambonie]

The linkage, shifter, clutch pedal assy, associated wiring, pretty much everything from the donor.

[adams18]

ok. im planning on putting a newer engine in my pickup this spring. would it be easier to put the sm456 in now while im swapping the 208, or this spring when i pull the engine? thanks.

[Irish_Alley]

i would do it now cause you never know when you need 4x4. but i would look for a 203 or 205 if you plan on doing sum mudding. i have 350 sm465/203 combo haven't broke it yet, knock on wood. broke a axle shaft and axle (dang Dana44) lol. especially if you plan on putting those 38s on her i would go for something better than chain drive

[keller]

A 208 will stand up too 38's and 500hp. unless you plan to do 4wd burn outs lol.

[adams18]

well i wasn't exactly doing a 4wheel burnout. haha. i found that my pickup launches pretty good in 4low with the hubs turned out:) i guess my rear driveline didn't like that too much..it broke right at the ujoint on the slip yoke. so i drove it around in fwd for a month or so. then my buddy got stuck in a mud hole(he also has a swb chevy) and the toyota he was with couldnt pull him out, so i gave it a whirl..in front wheel drive mind you. haha. pulled him out of the hole and right as i got out of the throttle, something gave way and it wouldnt go forward anymore. i got out and inspected everything..nothing looked broken. got back in and put it in gear but all it did was clunk and grind. no sound in 2wd but once i put it in 4hi or 4lo it talks to ya. haha. so i think i will take the sm465 and 208 from my 3/4 ton long box donor and put them under my pickup. also make a somewhat custom driveline from the donor's to fit my shortbed. Thanks for the help.

[Irish_Alley]

not to tick you off Keller but i never heard of any 208 standing that much power even the Dana44 cant handle that much. i could be wrong wouldn't be the first time. but allot of people i know first thing they do is get rid of the 208 and go with a 205 or if they have to a 203

[werewolfx13]

The 203 really isn't any stronger, its just heavier as its a cast iron case. Its not a matter of horsepower that a 208 will handle, because it WILL handle 500hp..its how you use it that will break it. If you're wanting to wail on it in the mud, rocks, or pavement, yeah, you're gonna trash a 208 eventually. You'll probably trash a 203 as well, you just wont blow the case apart as easily. A 205 is a stronger case because its a gear drive, not so much because its a cast iron case.

[Irish_Alley]

i put my 203 threw heck blown both rears and she still strong with my 38's