1956 GMC's did have chrome emblems. 1955 left over units were used "half built" and finished as 1956. Seen several, had one. 1955 GMC 2nd series, Task Force, Blue Chip truck released mid year was 12V on the optional Pontiac V8 and 6V on the 6 cyl, then in 1956 all were 12V as you say. The 1/2 T had 6.70 x 15 Tubeless tire on a one piece wheel. I think split rims were on 3/4 T and up. The 6 cyl was a 248 in 1955 but if built as a 56, that would be your 270. Don't forget that in the past 57 years, previous owners can add/change engine, transmissions, front clips, rear ends, emblems and all manner of parts from different years and models creating a hybrid. All the 1/2 T had 6 lug wheels, 3/4 T had 8 lug. (I believe there was a 15" two piece wheel and a 17" three piece wheel, both Kelsey-Hayes)
