In the timing belt kits, there is a water pump gasket that I haven't found a use for yet - It might be that "triangle" gasket you are referring to. Round hole in the center, and (IIRC) 3 bolt ears around the exterior?
When I replace the water pump by only pulling the front half of the housing, there isn't any place for that gasket to be. I suspect it is for the back of the housing, but that is only a guess.
Corey, if you are building kits that could possibly overlap (and obviously nobody wants duplicate parts) it might be helpful to list on the website somewhere which kits might be needed for which jobs - So someone buying a valve cover removal kit knows they will need the timing belt kit, (at least as a suggested purchase) and then the Valve Cover kit might only be the crush washers, o-rings, and the valve cover gasket. The optional add-on would be the rocker set since they are obviously going in there for a reason. The valve cover kit and timing kits could be the suggested purchases for someone looking at the rocker sets too.
And maybe (if you really want to be nice) one of those spring clips and the plastic T for the return line? I haven't broken any of them recently, but on my own CRD, the bottom of one of those return tees snapped off in the top of the injector. Just below its own little o-ring, the plastic must have been very dried out. That was moderately annoying at the time.
A head-removal kit could further build on the valve cover kit and timing kit, by adding gaskets for the thermostat, exhaust manifold, turbo oil return, and turbo oil crush washers. Of course the head gasket would be needed... Maybe they can be sourced separated from the bolts through The VM Specialist? Somebody must be the one manufacturing these.
If each kit built on the one before, then the purchasing / packing might get a bit easier on your team too - Job X is being done, so customer orders Kit A, kit B, kit C... And a side of fried wonton.
Thanks for doing what you do, and rocking it. I know Brian was pretty happy once we got everything resolved and running again. It was a little hairy with our two schedules, but you saved the day again.