I'm buying some 3" shorties on Imco Extreme uppers.
How many inches of spacing do you think I'll need?
I'm going to run 5 blade propellers & I'm guessing that I'll need 1 inch mabey a 1/2.
What do you think? I mean besides I'm stupid for sinking this much money in a 99 29 Outlaw.

Depends on where your propshaft centerlines are in relationship to the boat bottom.

Mine are 3" below the bottom and I have boxes,
I tried 2" shorties ( putting them 1" below) and couldn't get on plane, even with 5 blades.

A boat without boxes will have to be lower.

I doubt you will get away with anything more then one inch shorter then stock.

Just seems that no one has luck with 2 inch shorties on Baja's.

I would buy 2 inch shorter and be prepared to add spacers.

Keep us posted.

P.S. There are a lot of other things worse to spend you money on!

I think I'm going to go with Stellings boxes. I'll start 1" down on the box, then neutral then up an inch, if I get that far. Then box all the way up & drive spacers 1/2 down at a time. Or just leave it alone.

Neutral is the top holes,( zero shaft angle, zero raise)
1" up is the middle,
2" up is the bottom holes.

I've been told that if you use the bottom holes
( highest position) you should also raise the
engine, due to severe drive shaft angles.

Every one I've worked on has been in the middle position.

The drives are on a 32 Outlaw right now. No boxes. 5 blade wheels done by BBlades.
I guess I'll know in a few weeks.

Interesting, best of luck and keep us posted.