The mancini one fixed a very pesky rear main seal leak for me & others have that exact same style. I'm not sure why it worked, but I'm sticking with it. I also used the silicone 2-piece seals, the good side seals, assembly lube, VERY thin smear of RTV on the mating surfaces & offset the seals. Check Hughes Engines, I believe they carry the same rear seal retainer. I used their directions for installation.

70 Roadrunner convt. street car 440+6, NOS, 4-spd, SS springs '96 Mustang GT convt. street car '04 4.6 SOHC, NOS, auto, lowered "Officer, that button is for short on-ramps"