I purchased an '86 K10 one time with a freshly built 6.2L. It left me stranded one day, and it turned out that the bolt on the camshaft gear was not torqued properly. It caused the key to shear on the camshaft, so it stopped turning the injection pump. A new key with a properly torqued camshaft bolt and Blue Loctite fixed me up.
I've never seen an engine with no IP mounting bolts; that's weird for sure. I would think there would be resulting damage due to the IP moving around.....
Casey
1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter