Yes, I have hi-pinion in the front and Taco/TRD in the rear. No, they are not interchangable. The housing mods are the same, but they are not identical. They are a mirror image of each other, very slight differences between the new stud locations and the location of the notch that you have to cut.
Here, this is a link to a diagram I made of the gasket for the front hi-pinion locker:
http://www.yankeetoys.org/documents/...nionGasket.pdf
If you print 2 of these (you'll need a tabloid-sized printer to be able to print it full-sized), then flip one over and lay them on top of each other on a light table, you'll see the minor differences.
I really like how the hi-pinion fits, my front driveshaft is almost level. No issues with extreme U-joint angles. I can drive 55-60 mph with the front hubs locked, no vibrations.
Here's another write-up of a retrofit, I took all the photos:
Outdoor Recreation Network - Off-Highway, Jeep, & 4x4 Fun