Pain in the REAR
 

So, my 94 V6 Maro's rear end bearings are finally giving out after like 190,000 miles and i'm pretty limited in the dolla department, so i went to the local pull-a-part and found a 97 possible donor. The only thing is, the 97 is an automatic with disc brakes while my setup is the t5 manual with drum brakes. Will the newer rearend slip right in and if so what do i have to do to get the speedo back right??????? if not, what other options do i have???

If the donor diff has the same ABS arrangement as yours (which I believe it should), it will bolt in. But the gears are what you need to be concerned with. Most autos have taller gears than the manuals. The next part I'm unsure about, maybe Stan will chime in. I don't know if the 3.4 speedo is computer driven. I know on my 3.8, I had to have the speedo fixed with a tune, no poly gears to change like the old days.

Taller gears will just give it a lil more acceleration and a lil less gas mileage right?? and would the tach be affected as well as the speedo???

Taller would mean less acceleration, short or low gears would give you more. Yes, the speedo would be affected, not the tach.