They work best on a cast pan with a flat mating surface.
Used one on a stock-type pan and did not have good luck because
of all the stiffening ridges on the pan did not match up well with the tray's seal.
This was a couple of years ago when they first came out, so maybe they
changed the design.
Joe
If you enlarge the picture in that link
I agree , especially with the area around the dipstick , not even close on the factory 402 Oil Pan
And other areas where only one of the two silicone rubber o ring material would seal along side the stiffening indentations of the factory oil pan
Didn't work for my 402 Oil Pan
