[blykins]

The original FE's had rope seals and were not aluminum.

You can pretty much expect a leak from an aluminum FE block. It's just the nature of it.

I haven't had (knock on wood) a cast iron block rear main seal leak in forever. Seriously, I can't remember the last time.

I don't use the side seals and nails. I use silicone. Works perfectly, doesn't take forever to shape the nails, and you don't have to worry about the varying side seal cavity sizes on different blocks.