Hey all, I found a 1979 toyota 4x4 for sale and the owner transplanted a 350 into it, ive researched up some info on what needs to be done to the drivetrain and the only piece of the puzzle im unsure about is the transmission, he says its an SM426 4 speed transmission, and i can't find any information anywhere about how strong these tranny's are and if it will hold up to the power of a 350, can anyone help me out???

Mike

 

well, it's a chevy tranny that came behind the 350. It probably won't last long behind a built 350, but it should do fine.

Check pirate4x4 they'll have a whole lot more GM info

 

Could it be a SM 420?

 

If it is, its a good transmission with a 7.00:1 first gear!!

 

It could be an SM420, apparently they were only used until 1967 and the motor was pulled out of a 73 3 ton chev, but who knows what parts are replaced when and where on farm rigs. Although the transmission is hooked up to a NP205 Transfer case which apparently is not compatible with a SM420 tranny, ill have to look closer next time i go check out the truck.

Thanks

 

The SM465 was hooked to the NP205. Could it be that?

 

lol yeah its a really strong transmission...and really rare!! They came in 48-67 Gm trucks and 56-68 Dodge trucks though...VERY VERY durable!!

 

Thats what i wanted to hear looks like i may be driving a 4x4 this year

 

Pics?

 

I only have 1 pic, apparently its an 80 toyota not a 79, but here she is.

 

SM420's are very stout. They were used from '48-'67 in all trucks from 1/2 ton to 2-ton and behind everything from straight-6's to big-blocks. A mere 350 won't do one no harm. Be aware though, age can kill one. The 2nd gear splines have a habit of wearing out causing the tranny to pop out gear (like mine does). There is no known cure for this disease other than rolling the dice on a different tranny.

Like said previously, it could very easily be an SM465 which replaced the 420 starting in the '68 model year and running until '92. Very easy to tell the difference, look for a PTO cover on the passenger side. SM420's only have one on the drivers side, the 465 has them on both sides. As for durability, 465's were also used behind everything up to and including big-blocks so they're plenty stout as well.

 

More than likely it is an SM465 w/NP205 T-case. Very common. Very, very tough. Tougher than the 420 and easier to get parts for.