We have a tru-track in our 70 Road Runner with a Strange 60 rear. It used to have an 8-3/4 with a sure grip. The difference in how it drives is noticeable. There are some curves here that are sharp uphill steep curves. The sure-grip I could feel the inside wheel slipping and chirping on the turns (it was set up pretty tight for the drag strip). With the Tru-track it goes up the same curves like an open differential. At the drags trip it also locks up so an excellent device. The cornering question was a primary reason why we went with the tru-track over the Detroit Locker, as we use our car regularly on the street which includes our dirt road which can be slippery in the rain.

At the time we got the axle assembly from Dr. Diff the Detroit Locker was slightly more expensive (maybe $20-50, minor compared to the whole axle assembly, it was not the deciding factor by any means)than the Tru-track. Maybe that has changed? If you have the money and rules allow I would choose the tru-track. I think the tru-track is available for the 8-3/4.