3 on the Tree question

[Grandpas71]

I just bought my first classic truck for restoration. This was my wife's grandfathers truck before he passed away in 1995. It's a 1971 LWB C10 6 Cylinder with 3 on the tree.
Last weekend I removed the gas tank due to no fuel issues. I was thinking the inside of the tank might have turned to varnish since it had sat for so long. So, with the tank out of the truck I thought I would take out the sending unit and float assembly. Found that the "sock" was ripped and the tubing was blocked with muddy looking corrosion. Cleaned it out and installed an inline filter after the tank, runs like a charm!!!

Now I'm wondering what to do with the tranny. Don't get me wrong, my only two cars are straight drives. I love to shift my own. However, my wife only drives autos. I would like to make it more user friendly for her to drive occasionally. And she will not learn to drive a straight drive. But anyways.... What are the dimensions of the current tranny? Model number? Does a turbo 400 slide right in it's place without a drive shaft change? How about a Turbo 350? I'm just curious what's involved, and general information on this three speed tranny.

Thanks,

Grandpas71

[Longhorn Man]

Welcome to the forums!
I'm moving this to the truck board for you instead of the suburban board... more traffic and more vehicle specific.

[68gmsee]

Welcome from Texas...

Re: the change to automatic.

I did that to my 69 Chevy 20 years ago -3 speed column shift 250 six cylinder to 350/350 automatic.

Lot of work involved in the change: radiator, transmission, column shift mechanism, levers and bellcrank for the frame, crossmember for back of transmission, possible driveshaft shortening (you may have to just check that after you do the conversion). There are different transmission extension housings to consider.

Your best bet is to find a donor truck that is an automatic that you can take the parts from otherwise it will be harder to find the individual parts.

Consider it a hobby if you like to do this type of work, otherwise, I think I would leave it stock like it is and fix it up as a tribute to her grandfather. Let her ride with you and she'll enjoy it.

My wife is the same with manual transmissions but loves to go riding in my 68 GMC..

[capev86]

i can appreciate your situation....

but on my 72 suburban 3/4 ton 2wd, i'm keeping the 3 on the tree to be a bit different and keep some of the truck original. also, the saginaw 3 speed is a stout unit. i will eventually be swapping in a 406sbc w/ 84 750QJ in place of the stock 307 and going with a more highway friendly rear gear than the stock 4.56 (thinking a 3.73 w/ a locker in that 14 bolt full floater). i thought about going with an auto and i have a good 700-r4 but the parts needed to do the swap (auto column, changing the pedals, etc) wouldn't be worth the hassle unless the truck was off the road for a resto (not in that bad a shape yet).

the 3spd has a clutch (no slippage) whereas you have to wire up the lockup for a 700-r4 and then you have the extra cooling demands on the radiator. towing with a stick just requires the right touch and i can handle a clutch well enough not to burn it out with a big trailer hitched up. i have a dinky radiator in my burb because of the manual trans and no a/c, but plan to put in a bad boy 4 row for the extra cooling capacity and maybe turn the trans cooling portion into a stealth oil cooler. i definitely suggest an electronic ignition upgrade.