After recently making some chunks [1st gear] in my stock M-20 Ive decided to upgrade the entire trans. Since this is mostly a cruizer that gets beat on every now and then, I plan on keeping a 4 speed in her. I also plan on keeping the org M-20 and re-building it for another day...

Qs--
What 4 speed to go with?
This a mild >500hp built 427. Again, mostly cruiz but gets beat on every now and then
Super Case- M-20, 21, or 22?
I see there are a few out there that sell the Super Case. Experiences??
What about a ST-10?
Fitment??

I've done what research I can in the little time I get.
Please school me----

Thanks

IMHO the M22 is best suited to handle the ponies your putting out, but it really also depends upon your rear gearset as well. The lower the numerical gearset, up to 3.31 would best be suited with a 20 the 21 and 22 are virtually identical with the exception of gear helix. There you have it. The Super T10 is a direct swap, the iron cased versions are remarkably stronger than the aluminum cased counterparts. Supercase is a great thing.

After recently making some chunks [1st gear] in my stock M-20 Ive decided to upgrade the entire trans. Since this is mostly a cruizer that gets beat on every now and then, I plan on keeping a 4 speed in her. I also plan on keeping the org M-20 and re-building it for another day...

Qs--
What 4 speed to go with?
This a mild >500hp built 427. Again, mostly cruiz but gets beat on every now and then
Super Case- M-20, 21, or 22?
I see there are a few out there that sell the Super Case. Experiences??
What about a ST-10?
Fitment??

I've done what research I can in the little time I get.
Please school me----

Thanks

The M22W, wide ratio, would be right up you alley. As for the ST-10 being a direct swap, if you don't count the fact it is 3/4 longer, has a fine spline input and a 32 spline output and uses a sligtly different shifter, then it's a direct swap:noway::noway::noway:

The super case trans can be had in any number of configs and would be a direct swap if you wanted it to be:yes::yes:

Many people have these units, some are mine, and they seem to be very happy. Believe me, if they wern't they would make it known:D:D:D