SM420 and Driveline Q's...

[MrDanB]

My '57 3100 stepside had no trans in it when I got it last weekend...I know it was a 4-speed before the previous owner yanked it. What years of SM420's will work in a '57? I have a truck bud trying to sell me his SM420 out of a 66 rig. Will this fit in the '57? Also, I have no driveline. I was reading up on drivelines and seems that some got "torque tube" and some regular yoke? Anyway, Anyone got part numbers or pictures of a stock driveline? In particular a length to work off of would be great too.
Thanks-Dano

[5Mike7]

First, your truck won't have a Torque Tube.

The issue is the mounting of the tranny, and if you're staying original.

The original tranny "hung" off the back of the bellhousing, and the bellhousing mounted to the frame. I'll go take another look at my '59 to verify this later today, but pretty sure that's how it is.

The original mounts for the engine were at the very front, sitting on a couple of maybe 3/8th's bolts/mounts.

I "think" that the later tranny would still bolt to the original bellhousing though, although I never tried.

Thing is, if you're going for a more modern V8 and are going to run clamshell style motor mounts, then you'll want a later tranny that uses a cross member at the rear.

I'll see if there's enough light tonight to take some pic's of mine when I get home...it's got the 235 in it, but other than the length of the engine bolts/mounts in the front, it's the same setup as a V8.

[MrDanB]

Thanks Mike! I will peek through the gaping hole in the floorboards and get a pic of mine as well and see what's up under there...
Dan

[5Mike7]

Hey Dan,

I just read your other post, saying you had a 265 in the truck, so you must have the front mounts, and unless the engine is propped up somehow in the back, you must have the correct bellhousing on it.

You probably also have the clutch disc/pressureplate and FW on the enngine as well...

I have a later styled 4spd out back, when I get home, I'll measure the mounting hole spacing and the spline count on the input shaft so you can then do a little measuring and (you may need to pull the BH) count your splines on your clutch disc.

[MrDanB]

Well, you are correct sir! I do have the bellhousing still attached to the engine and I see how it bolts to the trans mounting tabs (angled in). Luckily, I don't have the shifter boot cover , so I have a lovely gaping hole in the middle of the floorboards to look through. Here is a few pics to show the bellhousing...BTW, when I look through the hole in the floor and shove in the clutch pedal, I see an "arm" on the left side of the bellhousing moving in and out. I also have some sort of adapter or flange sitting there in the mess...
Dano

[5Mike7]

Ahh, it bolts to the crossmember, not the frame (age is affecting my memory), got home too late to look at mine last night. I think what you see there is what's left of a throwout bearing.

[MrDanB]

Since I don't have a manual for the thing yet...If I get a new SM420 and bolt it up to this bellhousing...Think it will work? Or would it be better to remove the engine/trans and go through everything?
Dan

[5Mike7]

Well, since you asked

If you're not going to put it bak like factory, no reason to consider a 4spd granny tranny...they're pain to drive daily.

But if you're on a budget, and the engine runs well in the truck now, then go for it, other wise a 350/TH350 swap is cheap and easy, a 350/700R4 (AOD tranny) is a little bit more, either are very much improved over the truck transmission.

You mentioned in your PM to me yo didn't have a grille for it, or you just didn't have it on? I have a '57 Grill and a few 55/6 grilles too, depending on what your plans are.

[MrDanB]

Mike, The guy I got the truck from has a grille and "a box full of miscellaneous parts" for it...i will have to get over to his place and check out what he has. The next step is to see if the engine runs. I have a key on order through LMC right now. IF the 265 runs fairly well, then I will leave it in and work on the SM420 and driveline to at least get it running. Mostly so I can move it around while I work on it...I had originally thought 383 stroker or 406 w/350 trans, but I see naw that it is not a direct bolt in for the 265. I am more concerned about getting the cab re done before winter (interior) and getting a windshield put in... My friend in the local Camaro club has a 55 2nd with a clip he grafted on. He has a built 406 w/OD trans and 12 bolt posi. He loves that thing and it handles like it's on rails! Maybe down the road I can think about that sort of thing. I have other cars to drive and a Ram truck for now. I still need upper inside door metal pieces, some knobs and cables for the dash, upper grille piece, tranny boot/cover, etc. I'll keep ya posted.
Dan