jar84203

I've got a 66 Dodge Coronet with a 318 Poly and 904 trans. My question is will the trans bolt up to a big block, or would a different trans be needed? Thanks in advance.

78D200

You will want/have to bolt up a different tranny. While the 904 tranny is a good tranny, it won't last long behind a big block. Plus you would need an adpator housing to make it work. You would be better off finding a 727 big block tranny out of an RV.

jar84203

With a 727 out of a RV need different gears? And where would I find them?

Crazy4Carz.Com

No need to swap gears unless you want to.

jar84203

So the gears are different? Would you happen to know the ratios of both off hand? Thanks, I'm new at this.

Crazy4Carz.Com

Nah, the trans gearing is the same.

craveman

i guess some of the rv's had a bigger first gear for more torque. i think it was a factory option though inside of the 727. i was going to buy a 440 and a 727 but the guy said it had the optional 1st gear so it would suck in a car

Mopar_71

I agree with the 727 trans. It was made for HD small blocks and all big blocks. Except the hemi. It was built different for that application.
The 904 has a small block bell housing and you need a big block housing.
It won't mount to your big block the way it is now.

We are assuming the RV 727 is a A727B.
I have never seen or heard of a lower geared automatic transmission. I'd ask a transmission shop about that. Check the lower left hand side of the bell housing for the family group and the serial number should be located on the drivers side of the oil pan rail.

Another thoughts are you might need to change your driveline yoke becuase of the different splines and the length of the drive line may need to be shortened.
You might need to change your carb to tranny kick down linkage.
There are kits for your motor mounts out there too.

Just throwing out some ideas of what you may be in for.

Let us know how it's going.....
Mopar_71