The Stovebolt Site Forums The Shop Area Engine Shop Another tranny question

My transmission casting # is GM 590474. I know I've seen where to ID it, but can't seem to find it now. Can anyone help me out? Thanks.

If you go to where you can view recent posts of mine and go to where xram53 told me to go I think this will help you.

Its the one that says what kind of transmission

Here\'s a web page with a listing of casting numbers for SM420/465 transmissions. 590474 is from an SM420.

Thanks for the info Curt. I don't mean to sound stupid about this, but I just want to make sure that the SM420 is a 4 speed. Any way to determine what year it was made? Are the parts sold through Jim Carter, etc. for 4 speeds correct for this tranny? I really appreciate all the help.

I have to make a correction here. This particular casting number came up in previous threads, one of which I responded to and had forgotten. See here.

The consensus is that, despite what the web page I linked to shows, this casting number is from the SM420's predecessor, which is the '31-'47 non-synchro 4-speed.

To date the tranny, you can look for the case casting date code (a letter followed by 2 or 3 numbers cast into the case), and/or the tranny serial number (stamped onto the top rear end of the case).

I'm not sure about parts availability for these old pre-SM420 transmissions.

Is this tranny out of your '40? If so, it could be the original.

Yes, it is out of the '40. I've thought all along that it's the original tranny, although there have been some changes over the years that have me questioning everything now. The engine was swapped from a 228 to a 216 and is now going back to a 228. The rear end appears to be a later model. The brake backing plates are the giveaway there.

Anyway, I've got all new bearings on order for the trans. I'm using a local bearing house and have just given them the #'s off of the old bearings. I just wanted to make sure that I'm ordering the right gaskets, etc. for the tranny.

I'll ask George how his rebuild went. We've chatted a few times here on the 'Bolt.

Also, I read K10's posting on the thread you referenced and I have to say I agree. The reason I bought this truck was not for a smooth ride and ease of driving. I bought it because of its character and personality. I want a truck that's as original as I can make it. That's why I took the time to find a 228. I'm not sure what I'm going to do yet about the rear end but time will tell.

Thanks again for the input Curt. Man, I love this website!!