Thanks for effort to find a pic.

I looked at a couple of long block pics on ebay and, if there are freeze plugs on the rear of the engine/heads, they're very small. That leads me to believe that it could be a head gasket leak......but the pressure with which it's spraying out seems unusual (and I've had not other signs/symptoms of head gasket issues).

Under the circumstances, I may grab a bottle of the best head gasket quick-fix junk and can find and see if it has an impact. Otherwise, the truck has too many other "need to be done soon" things to justify a top end job (which I'd do myself).

Thanks again for the quick help.