Hi everyone. First post. 1990 e350 non turbo started chuffing, occasionally ticking/knocking, eating oil, comp test showed 400-450 all around except for #1, which was 200. Still had good power with no smoke, but the idle was rough and the chuff/tick was getting worse. Rockers, pushrods, lifters all looked to be without any flaw, so i took the heads off and brought em to a place called Cylinder Head Exchange in Sylmar, Ca. They got back to me in a couple hours saying that both heads were cracked on the intake seats of #5 and #6 and that there was nothing they could do. Said that i should find new heads elsewhere. Went back to pick them up and although they marked the two cracks, i cant see anything. I cant see anything at all on #6 and can barely make out an almost microscopic line about 1/8" on the seat of #5. Im unsure where to go from here because both of those cylinders had good compression, and the shop didnt provide any info beyond those cracks. The shop seemed professional, but maybe it was the wrong place for a strip/advise and i should get a second opinion? Or should i just bite the bullet and buy some rebuilt heads? Also, if surface cracks can be so invisible on the heads, id assume it would be the same for the block. Any tips for inspecting the block mating surface. I still havent cleaned either side since removing the heads.