904 tranny

[hockeydad1189]

hi i am looking to pick up a 73 duster it has a modified 340 engine .has a 8 3/4 posi rear with i am told 3.55 gears . i am told it has a 904 tranny is this the correct tranny i thought the 727 came with 340 engine is this a good tranny and will it hold up also the guy i am buying it from says the tranny has had work done on it ,but doesnt know what was done thanks jim

 

[Locomotion]

340's only came with 727's. After all these years, there are a lot of things that may not be original, including the engine! 904's are great little transmissions. But they all need at least a good shift kit to help them live if you run them hard. But there is no way to know what kind of shape everything is in, especially if even the current owner doesn't know. Take it for a drive and hope you can determine how well it works then.

Make sure if it's a 340 and not a disguised 318. Check the VIN to see if it's an original 340 or 318 Duster.

If it's an 8 3/4" rear in it, then that has been swapped in also. '72 was the last year of 8 3/4's in A-bodies. Biggest they got was an 8 1/4" rear.

Check bolt patterns. The 8 3/4 may have the OEM 4" bolt pattern. If front brakes are disc, it should be 4.5" up there. I believe drums up front would be 4".

 

[connerray]

Peak under the back, if the rear opens in the back its not a 8 3/4. 83/4 only way to pull gears are from the front of the housing.

 

[fishy68]

If it truly is a 340 car it should have a 727 but like Myron said as old as it is anything could have been changed out and the 904 will do the trick just fine if prepped right. The only problem is the statement by the owner that he says it's been worked over but doesn't know what was done. How can you know something's been worked over and not know anything of what was done??? Big red flag IMO. So many cars get passed off as having bigger engines and more/better performance parts than they really do you have to do your homework good to make sure what your buying is what it's supposed to be.