i was wanndering how much horse power and torque can my 69 3 speed tranny handle i was thinking of turbo charging my slant six

Are we talking about a 3-speed manual or a 3 speed automatic trans?

If it is a 904 automatic in good condition, it will handle the added power of a turbo. If you really get the boost high, you can install parts out of a V8 999 trans and you are good to 400 HP.
DD

If it's a 3 spd manual it can take the power, bur the non- synchro A-903 isn't too much fun especially if it's a 3 on the tree. At that point I'd be on the look out for an A-230 floor shift, or a four speed to replace it. FYI, some late 60's, early 70's mopars came with 3 spd. manual shift trannies so they can take the heat.

I'd guess you have a PRNDHL though,

-D.Idiot