I used one in my '68 Power Wagon. It was great when pulling trailers over mountains etc. Worked great and was easy to patch in. The trick is to know where you timing is at the full range of it's adjustments.

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)