I have used K$W Block Seal, I had a 87 yj that the block was creaked on the left side between to the 2 freeze plugs. Ran it fore another 2 years! In fact it's been setting for over 2 years and still has coolant in the radiator.
86 CJ7 5.7 vortec. 4L60,D44's,OBA,Air tank bumpers w/D rings detroits,4.88,35" bfg, mt's 9500ti warn
86 CJ7 2.5 detroits, OBA 4.56, air tank bumpers, w/D rings,9500I warn 31x10.5x15, Trxus
86 CJ7 bone stock, w/factory 44 never seen the dirt soon to be for sale
87 Wrangler also never seen the dirt.