Arg! How to separate form-a-gasket?

[2014 Warthog]

I've removed the front diff in preparation of changing the gears, removed all the bolts holding the front plate to the gear housing. But 30 year old factory form-a-gasket is just cementing the two together like a rock.

I can't even fit a razor blade between the mating surfaces. Using a screwtriver to pry or pound against the edge of the cover results in chipping the cover itself long before separation.

Any tricks to getting the two parts to separate? Is using a blow torch to heat the mating surfaces ok? or even useful to try to soften it? I don't want to weaken the cast metal if that's a concern.

The back had a gasket and came right off

[Edit] Got it off!

Had to dremmel a slot into the cover at an area that wasn't that structurally important, then head the rim up with the torch, then mallet a screwdriver into the slot till it popped off finally.

 

[joeynational]

I think a torch would be ok as long as you dont get to crazy with it. Do you have a large dead blow hammer? Smack it with that or a block of wood and regular hammer

 

[RonJR]

Do you have a large dead blow hammer? Smack it with that or a block of wood and regular hammer

This^^. Generally the secret is to find somewhere you can hit it with a large, heavy hammer. Heavy low-velocity blows seem to be a lot more effective than pounding hard with a light hammer. I've never had a diff cover or transmission/tcase successfully resist a few blows with a 3 lb sledge and a block of oak 2x4.