trans swap options?

[oem4me]

As my username would indicate, I normally don't like to deviate from stock, but I just can't make friends with the granny low four speed in my 1965 suburban. At this point, the truck is all-original and totally unmolested. 45K miles, one previous owner. It kills me to think of bastardizing this beauty, but I just hate that noisy tranny.
What are my options for a direct swap, requiring no permanent mods, that can be reversed easily if I ever want to. I'm guessing a later O.D. unit would be nice, if one would fit with the shifter in the same location. The motor is the 283 V-8, if that matters. Opinions?

[jonzcustomshop]

I'd just be on the lookout for a stock powerglide setup, or maybe a gmc hydromatic(?) -not sure if that would bolt up to a sbc..

[blackedoutharley]

If the trans is making noise and you're not otherwise opposed to keeping the SM420 and how it performs, why not just have the trans rebuilt?

I switched to Redline MTL trans oil and have been quite happy.

[Clyde65]

what about concidering a modern transmission like a NV4500 ( I think that is what its called) it is a 5speed and you already have a 4speed, talk to Clinebarger to get some of the perticulars, also if someone out there has doen the swap, they could guide you.

[oem4me]

Originally Posted by blackedoutharley

If the trans is making noise and you're not otherwise opposed to keeping the SM420 and how it performs, why not just have the trans rebuilt?

The current trans may be prematurely worn (only 45K), but weren't these units noisy from the get-go? Also, I've got almost no use for the granny gear, and a highway gear would be sweet.

[raycow]

Originally Posted by oem4me

I've got almost no use for the granny gear, and a highway gear would be sweet.

Your application is made to order for a T-5 5 speed transmission from an S-10 truck. I put one in my 60, replacing an SM420, and I couldn't be happier with the results.

Ray

[Scot_Douglas]

Originally Posted by lakeroadster

No way to pull that off though without cutting a different hole in the floor, right?

Does the burb have a removable trans cover like the trucks? The poster could always grab another cover to cut up (although, i just realized it does nothing for saving his OEM sound deadener / rubber floor)

[raycow]

A 4 speed burb should have a high hump (removable) just like the pickups. The floor covering could be a problem though, unless you remove it intact and put down a substitute covering until such time as you decide to restore the truck to stock. The specialty parts vendors do sell repro covering, but it will never fool anyone into believing it is original.

The floor requirement could eliminate just about everything which has a floor shift. Even an NV4500 shifter comes through the floor to the rear of the SM420. This leaves you with two possibilities, one expensive, and one a bit of work.

1. Gear Vendors OD, already suggested. No obvious downside, apart from the $. You will probably want to overhaul the SM420 though, as it really shouldn't be making any noise in 4th gear, especially at only 45K miles. That one is a real head-scratcher unless it was run dry at some point.

2. 3 speed w/overdrive shifted on the column. If you do a column swap it would leave no permanent scars. It would always be reversible as long as you keep the original column in a safe place. Finding a 3 speed column and linkage shouldn't be too difficult, as the rodders here are always pulling them out so they can convert their trucks to automatic.

Ray

[factorystock]

Originally Posted by oem4me

The current trans may be prematurely worn (only 45K), but weren't these units noisy from the get-go? Also, I've got almost no use for the granny gear, and a highway gear would be sweet.

Exactly, these SM420's were noisy from day one. Owners complained about the whine( especially 3rd gear ) when new. These old school transmissions were introduced in 1948, before the interstate highway system and last used in 1967. I am sure there is nothing wrong with your trans, its just the nature of the beast. The SM 465 introduced in 1968 was a big improvement and much quieter, but still a granny type, and would require a few modifications such as '68 bellhousing, larger pilot and throw out bearings.

[psycotruckr]

I am currently running an old '1962 t-10 that does a fine job in my 66 panel. thing about upgrading to a tko-500 to get over drive.

[TagMan]

I'm installing a NPG A833 3-speed w/OD from an '84 Chevy 1/2T this winter to replace my granny 4-speed.

[blackedoutharley]

What about adding a GearVendors over/underdrive unit?