I thought I'd have posted in this thread before, but a review says otherwise...
Off the top of my head (meaning I've probably missed some since I haven't inventoried them all by a long shot):
--A number of blue-box "traditional" K-Line cars, among them a CSX crane and its tender, the latter noteworthy for not having fast-angle wheels (something I discovered when I noticed its wheels making an unusual noise), and a couple of their 027 three-dome tankers, and one or two Christmas boxcars sourced from the KCC Toy-Fair open house, one or two other Toy Fair boxcars, a KCC "new look" boxcar from their upgraded traditional boxcar tooling, and a chrome-plated TTOS anniversary boxcar.
--At least six of the 027 cars offered as freebies to KCC members at K-Line's York presence.
--At least two of their two-bay 'traditional' hoppers (KCC and Boraxo)
--Up to four Five of their die-cast hoppers (four B&O and one ATSF), and one of the 40' die-cast boxcars (RailBox)
--A pair of their 50' flatcars (NS and CSX).
--Both versions of the die-cast Rock Island gondolas
--Two of their 16-wheel die-cast flatcars, one depressed-center, one not. (I think I got these at the KCC Toy Fair open house)
--Two extended-vision cabooses (Westinghouse and Conrail), two ex-Kusan cabooses (one NS, the other I'm not so sure of), and one of their shorty bay-window cabooses (ATSF) directly descended from Marx (and I believe, also acquired at a KCC open house at Toy Fair).
--Three single-unit Husky-Stack doublestack cars, a pair of the two-unit Thrall doublestacks, a single unit Thrall car, plus three sets of two-unit TTAX spine car sets.
--Four of their Roadrailer-like RailMate trailers.
--Three Plymouth switchers and 40 of the little two-axle hoppers that went with them.
--The Greenport Scoot set plus two add-on coaches.
--The KCC CSX SD70, Amtrak F40PH, Chessie GP38, two each of the Chessie S-2 switchers, 2 each of the NS MP-15's, one Kennecott MP-15 (plus the work caboose), one clear-shell MP15 prototype (came from our own Alan Miller) and one Virginian Train Master.
--Steam: scale and traditional NYC Hudsons, scale B&A Berkshire, and their first-issue ATSF 4-6-2 from the Marx 333 tooling, and the Pennsy A5 0-4-0.
--four or five of their Kusan-derived tank cars (Santa Fe and Ewing Oil)
--six (?) aluminum tankers (BP 3-pack, Engelhard, BN and BASF)
--five aluminum Centerflow hoppers (ATSF stainless-finish "Super Hopper" scheme), plus two more twin-bay Centerflow hoppers (Chessie)
--One of the voltmeter boxcars (UP)
--Four packs of ATSF and DMIR ore cars, plus singles of the KCC "Big Red Line", TCA (or was that TTOS?), Pennsy, and Great Northern.
--KCC Golden State E8 AA and eight of the 18" Golden State coaches. I'm only missing the second vista dome, the K4632-29841C "Golden Outlook" (and still looking for it). Some of these I got direct from the KCC Toy Fair open house.
--four 18" Amtrak Superliners.
--three coil-steel cars (BN, 2x BNSF)
Oh, and an addendum, 14 (!) additional aluminum tankers acquired this year via Cabin Fever.
[2023 edits]: Added an Alcoa four-bay ACF hopper, the yellow-band and green-band (10/2023) Santa Fe aluminum tanker from a four car set
I guess I can count myself among K-Line fans then 
---PCJ
Edit: 1/2/23: found my diecast hoppers and updated
