Is it true that only the TRD has locking rear diff. And if so is there anyway to put a locking diff. on a 4x4 tacoma sr5 withouth one.

From the factory, the TRD edition is the only Tacoma that comes with a locking diff. There are lots of different options to add one aftermarket on a non-TRD vehicle though. ARB offers one of the most popular solutions which used an air pressure activated locker.

It is also possible to add a Toyota electric locker to a non-TRD truck. However, it involves the replacement of many other parts in the rear and in the end is often much less cost effective unless you find the parts used.

If you want more details, I would suggest doing a further search on existing posts here and at http://www.tacomaterritory.com/forum/ .

Thanks,

Pete