I have a Petroworks spring over kit on my 88 Samurai.
I am currently running the red Gabriels that come with the kit, however Im missing the rear upper shock mount bar and have attached the shocks to the stock location.
I think this causes the shocks to be over extended and bottom out when I drive over a dip.

After reviewing the Petroworks, Sky and Rockyroad versions, I came to the conclusion that for a few dollars more its seems that the machined billet aluminum version from Spidertrax is the nicest one and best buy.  The other ones were all welded angle iron or bar stock.
When I talked to Calmini they said they don’t make one and even recommend Spidertrax too.

When I spoke to Brent at Trailtough he said it is not necessary to use the rear upper shock mount bar and that the stock location was the better way to mount them.  He said to just get longer shocks and that’s it.

So now Im confused as to the better set up.  Im sure they will all work, but I assume depending on your application one way will be superior to the other.

It seems that the stock location would be more stable on road, with less articulation off road and the relocation bar will give you more articulation off road and be less stable on road.

Im probably use my Samurai more on road then off, so Im thinking probably the stock location would be better for me?

Cliff notes:  Better to use the stock rear upper shock mounts or a relocation bar?  Pro/Cons of each.

Unless you need more droop I would stick with the stock locations.  You will probably get about 2" of additional down travel with the re-location bar.  It's up to you if you think it's worth it.

Then again, I'm probably a bad person to give an opinion.  I still use the stock lower mount locations as well. 

stock location is fine you just need to weld on some lower shock mounts if your using the stock one's fliped over on the spring plates, then measure between the two shock mount bolts and get some shocks about three and a half inches shorter and away ya go, mine are like twenty eight and a half inches long when extended but i'm running yj's so there ya go.

I found this on TT site, helped me alot

http://www.trailtough.com/default.htm