Sure. You dont have to do it before you install though. Just unbolt the motor and slide the gear all the way to the left (or is it right, I forget, try both)

You'll have to drive the truck a few feet and it will lock up. If you have it out of the truck, you'll have to turn the spider gears until it locks.

Then just move the gear the other way to unlock it.

88 4R, 350 V8, R150 5 speed Sold <...uot; />
97 4R, stock, daily driver
98 Sienna, kid and dog hauler, wife's ride