I'm building one to race, the newer case looks stronger (lockup) with the ribs across the top, but is it stronger? Got 5 from 74 down and 3 latter. I think there is a difference with the fluid holes between the two types. Just looking for some heads up from guys who have built these. Ton of info for the 727 not so much for the little brother.

Most all trans cases that get ribs have those ribs added to prevent case cracking - and usually in TRUCK applications and especially for those for 4WD applications. Earlier applications - car and truck on both 727 and 904 had brackets that ran from the sides of the engine down to the bell - to prevent case cracking there as well - but only on small blocks because those had shallow crank cases that stopped higher up from the bottom of the bell compared to B and RB engines. For a drag racer app - using a rubber trans mount and motor plate or solid engine mounts - you should not crack a production case. Given a choice - not a bad idea to use the ribbed case - it's suspenders on a belt.

Pre 71 904 cases - I think the breakpoint is 35xxxxx - have a smaller 2nd gear servo than the later cases. I usually use a 5.0 2nd gear band lever for the early cases and 4.2 or 3.8 arms on late model cases.

Good info so far

This is about the only real difference in the cases. Yes some truck cases had ribs cast into them but otherwise they are pretty much the same. I have a non ribbed '73 case in my car and have never broken or cracked it. Now the converter hub is a different story...

Would the Dynamic race converters have the hub problem?
How about that big spring in the front drum, I heard someone makes a better one?