Can a open rear end be converted to a posi?

weld the spider gears...your rear end will be completely locked, no slip. Google it, Im sure you could find more info, I saw some with diagrams even once.

Do not weld the spider gears. Yes it is cheap, but you will hate driving the car.

I did the powertrax lock right locker. All you do is remove the spider gears and add the unit in their place. Not that hard to do. They now have available a "extreme traction system" which should dissengage(sp?) a lot smother in the turns with the same straight away locking power.
http://www.powertrax.com/

I wouldn't weld the spiders either. Save that crap for a demo-derby car or a figure-8 thrasher.

The Powertraxx Lock-rite is certainly the way to go. I put one of these int he front diff of an '87 Ranger and I'll tell ya, it's impressive! I busted one of the front 2 axles and it still was pullin the one good front wheel with the opposite axle broke! Great units!

Another cheaper option, like welding the gears, is dropping in a mini-spool. I'd rather do that than well up the crap. I have a mini-spool in mine and it seems to be ok. Not something I'd drive daily. the mini spool replaces the spider gears just as a Powertraxx Lock-rite does. the Spool will be cheaper but you won't have the benefit of the unlocking Powertraxx for that city driving.

Back when I was young, I had a 200sx datsun beater car, and I blew up the stock spiders doing cheesy hole shots at 7k, so I had a buddy weld the carrier solid. Anytime I wanted to slow down, I didnt need to use the brakes, I just swerved back and forth in the road. How handy.