TH350 valve bodies differ considerably from brand to brand or year to year? My '71 Skylark had a shift kit installed when I bought it. Shifted too hard for me & it was replaced with a used body from a Chevy TH350. It had been drilled out for the kit. Bought a NOS GM valve body recently. Gr.4.265 # 6262089. This doesn't show in my parts book. Correct for '71 was Gr.4.265 # 6260306 /SUP/6260290-6260310. Trans. is working just fine right now, complete stock rebuild two years ago. No need to tamper with it. Might get the oil/filter changed before I store it for the Winter.