I am rebuilding an ofna ultra lx pro.I noticed a significant amount of play between the ring and pinion during my tear down.Is this normal or do you guys shim the pinion gear to eliminate it?

do you mean the ring and pinion on the front and rear diff ? if so you would shim the diff to make better contact with the pinion, if you shim the pinion it may make contact with the diff body under power..

Yes it is the front and rear diffs.Does any one make rinf gear spacers?
or would you shim the entire diff?I don't know if there is enough room in the case to move the whole diff over.
Thanks for the help.

yeah you can use the small shim spacers , you only need to shim it say 1 or 2 shims, they slip over the end of the drive cup and rest between the bearing and diff case, they can be a little tight to get in but they do fit.. they are really thin , like .1 mm or .2mm

Am I being over cautious or is it something I should take care of?

Definitely take care of it. If there is too much play it will be easy to strip the pinion gear (at least that was the one to go for me).

That is what I thought I'll pick up some shims.