The Hylomar I have is blue, and comes in a small squeezy tube. It's not like RTV at all. Hylomar doesn't really set as such (and definitely doesn't vulcanize) and is smeared on quite sparingly. I've used it most often on gasketed joints - either paper or cork. But there'll be folks along soon with much more experience than me
hylomar is oil,temp coolant and fuel aneorobic sealer, which is to say it settles when exposed to air/oxygen but remains tacky. for the purpose of sealing the case you can use "right stuff" silicone. it is a vulcanizing silicone and unlike rtv, right stuff is oil resistant which is what you need.
regular hi temp rtv will leak.
Don't use too much Hylomar Blue. Being non setting any excess beaded up inside will eventually come away and get into places it really shouldn't go. At engine temperatures the bead goes sort of tacky and hangs on for a bit but when it breaks away it comes off in large lumps.
Way back one of my trainees used too much when re-assembling a small Kawasaki. Stuff got everywhere inside. Horrid mess. Took ages to get all the oil ways clean again. Only reason he didn't loose the motor was forgetting to tighten something up so i got involved to sort the clunk before it had done many miles.
Like Chris I'm a Wellseal fan. Painting on so much more civilised than squeeze'n smear.
Agree with all the comments about Hylomar but the OP is replacing the chain in a transfer case so the only sealant he's going to need is that for the cover. The overhaul manual actually states a 2mm bead of RTV (the same as fitting a diff in an axle) but the recommended one is obsolete. Hylosil 300 is the current equivalent. Wellseal is a different stuff entirely.