Ray,
Was writing a long thing about the IP when you posted again. Oh well, fingers needed the exercise.
Are you talking about Figure 79, Cover, Item #8 and gasket, item #10? If so, then go ahead and order the front main seal, item #11. Might as well, cheap insurance. The white engines, for the 15 and 30 KW were notorious for leaking. Mainly from front and rear (figure 78, item 11) main seals. If you do the oil pan also. Figure 77, item numbers 5, (X2) and 6, (X2). And, a real sharp eye would also see, that all these parts are part of a kit, 5330-01-022-7993. The 7993 is the big gasket kit. It has it all in it. If you do the oil pan, be advised to use some sort of glue or a tacky substance to keep the side gaskets on the pan. The rubber end gaskets also can sometime be a PITA to keep in place. So we used weak spray on tacky crap, to keep them in place also. As me how I know.
Also, when putting the pan back on, and I know I don't have to remind you, but for the benefit of others who might read this, screw all the bolts in by hand, but not snug. Wait until all are in, then snug them up, kinda like a head gasket. Not all one side at once. Or not all one end and then the other. From side to side, like a head gasket. The pans can sometimes warp, or not go on just right, and LEAK. As me how I know.
We had so many of these leakers, that we decided to replace every 15 KW gen set in a battalion, (about 50) the front, rear, oil pan, and IP seals, along with a raft of other seal and gaskets. And on about 25%, was wasted time for the mains. The engines had been around so long, and "quick" overhauled at Tooele, Utah so poorly, that no one noticed that the cranks, in the main seal area were worn. So the new seals would start leaking again in 100 hours operation.
Two of my "problem children" were the Master Engine Removal Team. Those two boys could start a job, and 90 minuets later, the engine was hanging from the chain hoist. Poetry in motion. It was the only thing that kept me from tossing them out of the Army. And they were turbine repair guys. There is, or was, two different seal kits, the 7993 kit, and another one, smaller, but has the gaskets and seals for just the bottom of the engine. The kit is not in the TM. The only reason I know,is because we went and stood on the desk of the TROSCOM, (Troop Support Command) boss in El Paso and he got it for us. I can not remember the number. As it was smaller, cost less. The overhaul kit, 7993 is, or was about 200 bucks. The NSN has been replaced by NSN 5330-01-045-4162. Part # 40-3094660. In the TM, the part number has an "A" at the end. That's a mistake, TYPO.