What are some Key identifiers of a post 68 904 vs an Early one?Quote:
Concerning your SB 904...make sure your slant six converter is the same era 904. Pre-'68 904s had a different input spline to the torque converter than the '68 and up. A '68 and up tranny will have more upgrade options for a torque converter than pre-'68. As far as stall goes...the slant torque converter will flash a little hirer with that new found power in you 360.
A-904 transmissions from their inception until 1967 have 18 splines in the input shaft. Non-lockup transmissions from 1968 have 27 splines.
Lockup 904 transmissions appeared in 1978, and have 26 splines. A-500 overdrive transmissions also have 26 splines. The output shaft has 25 splines.
If in doubt, count the splines. It saves a lot of headache and stress later on when you might otherwise discover that you have the wrong torque converter or drive shaft yoke.
For small blocks, 360 engines and some 318 engines of the LA family are externally balanced. They use specific balance weights on the torque converter, and are not the same between the 318 and the 360. The 340 engines in 1972 and 1973 used cast cranks, and thus used their own unique externally-balanced torque converters also. (Allan)
The 5.9 Magnum engines are also externally balanced, but don't use the same balance weights as their pre-Magnum counterpart, so torque converters from the late seventies and eighties 360 will hook up but not balance properly on the Magnum motors. For big blocks, the 400 is externally balanced as well, so it should have its own particular set of balance weights.
Rick Ehrenberg wrote: All 318 (5.2l) engines - Magnum, SMPI, or carbureted - are internally balanced, therefore there are no torque-converter / flex plate swap problems.