G series motors (used from '41 to Sep/Oct '47 in trucks and cars) had blocks and heads with G in the part number, not H. A G and H are easy to tell apart, the H series hada modern looking distributor, unlike the G which used an older style non modern dist. The blocks and heads are different, infact, most every part is different between the G and the H. The H series will bolt in place on a G series chassis with no mods. I have a H series in my '46 that originally had a G series 6, and I use the original G series transmission.