When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The 302 came out mid-year in the '69s. Late '69 trucks will have two pairs of holes on each side of the crossmember from the factory (one set of holes to bolt in the lower ends of the I-6/FE engine perches and another set of holes for the lower ends of the 302 perches).
All Bumpsides prior to mid-'69 will only have one pair of holes on each side of the crossmember (for the I-6/FE perches). Naturally, a Slick wouldn't have the extra set of holes for 302 perches.
You can take the 302 perches, bolt the upper ends to the frame and use the holes at the lower ends of the perches as a template to drill the needed holes into the crossmember.
My '69 F100 has the factory 240 inline six but, it's also a late '69 since my crossmember also has the 2nd set of holes present in it from the factory for the 302 perches.