I have an AMC A904 that I plan on putting in a '70 Javelin (Mopar adjacent). I got the transmission with the car so I have no history on it. I am transmission ignorant so when I saw a numbered plate above the valve body I didn't know if it was stock or if someone has been in the transmission before. So, looking at the picture, is this stock?

Good news was the pan looked really clean (no metal).

Can't tell you if anyone has been there before, was the pan gasket cork? Since that trans is for AMC motor, I would at least have it resealed and would probably have it rebuilt. Its been around a very long time.

The gasket was not cork, black nitrile/rubber. I'd assumed someone had changed the fluid/filter before but wasn't sure about a rebuild.

I don't plan on keeping this transmission in the car too long, few months, so I'm going to roll the dice and put it in as is

Numbered plates are normal.

Wish I could say more except just can't tell anything else about it.

If you have never built a transmission 904 and 727 are pretty easy.
Good time to start.

That's what I was looking for. Thanks!!

I'll probably give the 727 rebuild a try once I find one.

a FSM and the monroe and hand books are good material to help you on the rebuild.
i refer to these often, just to keep my memory fresh.

The number in the steel plate is the last three digits of the plate's part number.

Thanks!

The 904 when built well will take a bunch of power for a good bit. Not sure what the end use of the car will be. I swapped from a 727 to 904 and the fluid looks perfect two years and 50-60 runs later.

I've done 904 to 727 before, id never go the other way

Funny, people have had simple 904’s live behind much higher HP/torque than most would believe. With big sticky tires.

Funny too that they seem to hold up for racing and not as much with normal driving mileage.

904 > 727 simple mopar math

I put a 340 in front of a 904 in a 69 Charger (originally had a 318), and added a 3:55 rear gear. Can't say how long it was going to last, but it sure was fun the summer I put it together and beat the crap out of it. The kid down the street wanted that 69 Charger body way more then I did and he became the owner of a 69 Charger with out the motor and trans. The motor eventually ended up in my dirt track car. The trans probably got sold.