S13 Heater Core = Impossible

[trpower7]

As I was trying to replace the heater core in my 92' S13 I have run across the roadblock that it is more or less IMPOSSIBLE to get to. I removed the dash, etc, and I can see where it is. But it looks as if you would more or less have to dissasemble the entire dash and HVAC system to get to it. Also, I have noticed a part # discrepancy. The heater core I ordered said it was for a 91-94, assuming all DOHC S13s. However, the core looks like the inlet/outlets are MUCH different. Can someone look up some part numbers, FSM pages for me??