Oh yeah, D for Memorial. Shoulda known.

Fascinating informatin -- thanks, guys. I had vaguely heard about a precancel maker (from Brunell's intro, I think), but I didn't know the name T.P. or the details.
wt1, can you post the web address / link, if there is one? I'd like to read the rest and maybe search on from there.
Meanwhile, another couple of i.d. problems:
1986: 50
1986 Coils: 1, 2, 3, 5, 15up, 25fup
There's a 1986 52c and a 56c, 2189/2190, but I am at a loss for a 50.
For the others, I have, from 1987: 2225, 2226, 2252, 2253, but I can't work out the 15 or the 25f -- maybe 2260 and one of 2278/2280? But the precancels read UP on them, so I have been trying to find a horizontal stamp, because it seems vertical precancels are less usual on vertical stamps.
Thanks again.