Im looking for about 3/4 inch rear lift blocks for my 92 stock toyota 4x4. but im not sure which to get. Im on the 4crawler page. should I get the custom width spacer or the 2" width spacer(my springs are 3 inches wide)? pressed in locating pin or no? do I need new longer u-bolts? anything else i need to install them?

As far as width, that is up to you:
- http://www.4crawler.com/4x4/ForSale/Shims.shtml#FAQ2

2" works fine, your springs are 2-3/8" wide and if it'll bother you to see the narrower block under them, then get the custom width shims to match your springs.

Pressed in center pin means you do not have to take apart your spring pack to install the block as you would with a bolt-on block. For that, you'll probably need a longer center bolt for your spring (unless you have 3/4" or more exposed thread on your existing center bolts):
http://www.4crawler.com/4x4/ForSale/Shims.shtml#CenterBolts

On the u-bolts, grab a ruler or tape measure and check your truck. If your truck has at least 3/4" of exposed threads on the u-bolts and they are in decent shape, then you'll be able to re-use them with the lift blocks. If you have less than 3/4" of exposed thread, then you'll need new u-bolts.

pressed in center pin is preferable IMO bc you don't need to deal w/ finding a new center pin and whatnot. in your case it'd probably just be bolt-on and go

so the standard two inch,with pressed in center pin needs nothing else? how long should it be?

Generally you want the block (or shim) to match the length of the spring perch:
http://www.4crawler.com/4x4/ForSale/Shims.shtml#FAQ2

4.75" is typical for the rear axle.

I only have 1/2 inch of exposed threads on the u-bolts.=(
where would I get longer u-bolts?

See if you have a local spring shop, they can bend up a set for you. Or try one of the big 4WD parts places and order a set. Or that is a good time to pop for a u-bolt flip kit, putting the u-bolt threads up on top of the axle, away from the rocks.

Or go with a 1/2" block, can't do those with a pressed in center pin, but with a longer center bolt, you can bolt them to the springs and call it good.

does mine take the 3/8 center bolt?(I noticed they have 5/16 and 7/16 also) Its a stock 92 single cab short bed 4x4. thanks for all your help

If stock, likely 10mm. In that case 3/8" fits fine and is what is used in most after market springs.