90 degree adapter leak

The 90* adapter base mimics the filter plate in mounting depths of the center boss and outer gasket surfaces, the LA and Magnum plates are different for a reason- due to the differences in the ways the Magnum and LA are machined at the filter. I got a 90 to seal on a Magnum by cutting my own gaskets of different thicknesses (thinner inner gasket and way thicker outer, IIRC, and lots of goop) to make up for the discrepancy, but it didn't last long, maybe 500 miles if I was lucky. I ended up throwing the stock plate back on it and ran a shorty filter...
To my knowledge all the 90* adapters are the same, inasmuch as they are for LAs- I don't believe there were any specifically made for the Magnums.