Volvo Penta SX-C Help

[ParkerPeformance]

Hello, I have a '95 Four Winns here with a Volvo Penta SX-C outdrive. Serial # 4112011465. Story is the lower gear housing was cracked when a dealer did not winterize is properly. That dealer put on lower gear housing #3855493D2. Ever since that lower housing was installed, it leaked from the larger o-ring around the countershaft. I have replaced that o-ring, cleaned up the sealing surface, and still when I pressurized the outdrive, it has a big leak around that casing, and when I spray with soapy water, I see bubbles all around it. So my question is; is it possible this lower unit is not compatible with this SX-C outdrive? It looks like everything lines up right, but I want to be sure and I can't find much information about the lower unit going off the part number printed on the housing.