I think that Philco used "L" for the light oak cabinets... I would guess that the chassis is the same.
jr
1952 brochure:
http://www.tvhistory.tv/1952-Philco-Brochure1.jpg
Update...I dug out an old Sams Photofact listing and they show 2 listings for the model:
52-T2151 (ch 41,D1,A) .... set 171, folder #9
52-T2151 (ch 71,G1)....set 179, folder #9
No mention of "L" (light oak blond), "M" (mahogany) or "W" (walnut) however, in the index.
Do you see a chassis # on the label or stamped on the chassis?
jr