Is there any chance I can use this one piece oil pan gasket for magnum engines, on my stock 76 LA 318?
https://www.manciniracing.com/mop59lmagoil.html

I want to say they don't, but not 100% sure. I think the differences is in the timing cover or rear seal diameter. It was a topic on here many years ago...

I'd call and ask before buying just to make sure.

It'll work. You have to fill in the gaps around the front seal (I used the permatex ultra black in the spray can) where the little kickouts in the oil pan are. Or, remove the front section and put in an LA front pan seal with a couple of small beads of sealant (stuff mentioned above will work) where the seals mate.

it won't work.
2 reasons it doesn't work.
magnum engines all use the 360 size seals.
5.2 or 5.9 are the same pan and gasket.

but even if you got it to seal, there is a lot of gap to seal.
Feets will tell you I am an RTV fiend. I will use a whole tube of the stuff on each side.
I used it on a 360 pan for a 5.9 and it still will pour oil out of the front and back.

I haven't looked in a while. but they did make a 1 piece for sb a while back. for the la type engines.

I have one, it's orange in color, on an LA 360 block and not a 318. I can'r remember where I bought it from! If it comes to me I'll post it.

Edit: Milodon versions on Ebay, but it doesn't specify if it's a 318/340 or 360 style.

Jegs list one for 360 but not 318 that I can see.
https://www.jegs.com/i/JEGS/555/210495/10002/-1

Read teh reviews

"This is a one piece oil pan gasket designed to fit a Magnum style oil pan. It does not properly fit an LA style oil pan due to the notches in the front of the oil pan."

Did you let Jegs know?

I didn't write the review and I have zero experience with it.

no info on the subject at hand but I just had an issue with the front gasket for the half moon (under the tcover) on a speedway mtrs new pan so be sure & mockup/check fitment as needed before you breakout the cement. the 2 different sized holes (on each end) in the pan for the nubs to be pulled into need slight enlargeing with a drill (no big deal) but another thing to check if needed in your deal. If the 1 piece dont fit or another 1 piece doesn't fit I would go with regular gaskets (& be sure to check pan bolt hole flatness). I dont care for cork but not sure what is out there. EDIT & on the cork you may need to cut the long length into several sections for the bolt holes to line up. MORE EDIT the pump to tcover gasket fits better flipped one way, mockup/flip it dry on the pump & you will see the best way, that it covers quite a bit better.