The two engines that were offered in 1969 in the SJ Grand Prix with a 4-speed were a 10.5 compression 370hp 428 that had an engine code "WF" and #62 heads. The other 428 was a HO engine with 10.75 compression and with an engine code of "WL" and #62 heads. The changes in the two engines were in the cams the std. 428 had a #67 cam while the 428HO had a #68 cam. Hope this info helps.
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