1943 Dated Letter with SS-Feldpost Ink Stamps

Envelope is marked with "Rastenburg- (Ostpr) 13 12 43 with ink stamp "SS-Feldpost" with oval Waffen SS stamp with eagle and marked at bottom "SS-Pz.Jg.Ausb.u.Erf.Abt.I" (hope I got the letters right) Address is in black ink. Backside at top has name in ink with another stamp' with "SS-Pz.Ja.u.E.Abtl. 1" "Rastenburg / O. Pr." "SS Kaserne" .Envelope is about 6-3/8 by 4-3/8. Envelope is in sound condition with some age and wear but nice. The letter in side is handwritten in ink and dated 13.12.43. Letter is about 10 inches by 8-1/4. If you can read, could you let me know what it says. Overall light wear and age. Exc. + $200.00