How do you install a five speed manual transmission in a Toyota pickup 1987 when the original was a four speed manual?

I did this myself. Your transmission will bolt right up to your motor, but because your overall length of your transmission will be longer, you will have to get your rear driveshaft shortened and front one lenghtened (providing it's a 4X4) then have them both high speed balanced. This can be done relatively cheaply ($100 - 150) at a shop that specializes in drive shafts.

I recommend checking all U-joints and changing them if necessary. Before getting driveshafts cut, call your shop to find out tolerances need for play when flexing your drive train, i.e. going over rough terrain, accelerating, etc. Your shop will tell you what to measure.

Then just bolt them on and your ready to go. It made a huge difference in my 22R pickup in mileage and RPM when hwy travelling.