As Gert stated, each model year for the PV444 had a single alphabetic designation, then either an S - Special, or E - Export (stripped down with no chrome bumbers, cloth over frame seats - a real el cheapo). In addition, there was a Q variation from Sept. 1950- May 1953 that had the Fix side signal lights, instead of the cuckoo (takgök). The basic model was always black, lacked the side trim and had only a driver's side sunvisor. Also, the hood lifters said 444 on the basic model and the swallow hood lifters were used on the S models. Although you could buy a black S, they were most often non-black. The interior on the basic model was blue/gray (green/cream on the A) versus the maroon/gray on the S. I also think the interior color on the basic model was gray, while the S used the same exterior color. The basic floor mats were blue/gray, while again the S mats matched the exterior color. The latter 444 models also offered more interior and exterior color combinations. So, here's the PV444 model variations (from PV-klubben):

PV444 A, AS SEPT 1944-SEPT 1950
PV444 B, BS, BQ, BSQ SEPT 1950-JUNE 1951
PV444 C, CS, CQ, CSQ JUNE 1951-AUG. 1952
PV444 D, DS, DQ, DSQ AUG. 1952-MAY 1953
PV444 E, ES MAY 1953-DEC. 1954
PV444 H, HS, HE DEC. 1954-DEC. 1955
PV444 K, KS, KE DEC. 1955-JAN. 1957
PV444 L, LS JAN. 1957-AUG. 1958

I'd say that Gert's is a DSQ (although I think it was originally a DS), while mine and the one for sale on eBay are both E models.
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Cam a.k.a. CVOLVO.COM