mat in tn wrote
the flareside should be held on with 6 bolts.
The 80's Flareside beds had 8 mounting bolts. The 1992-1996 Flareside had 6 bolts (I think?).
Here's what the factory bed crossmembers look like. The front two bolts go through the front sill to the frame, and the rear two sets of bolts go through the rear sill into the frame. The two sets in the center go through two of the three middle crossmembers. There are 5 pairs of wooden blocks, and all 5 pairs are different.
Here's what it looks like with the washers in place, before I put the bolts in:
I used all new crossmembers and sills on the bed from Mar-K in Oklahoma.
After this truck, I built a second Flareside bed, but this one almost complete from scratch. For the three middle crossmembers, I used 1/8" channel steel...2" wide, with 1" sides, cut to fit. I then cut the wood blocks at home, and sized them all to fit. I drilled 5/8" holes through them with a spade bit so that the 1/2" bed to frame bolts would fit with clearance. For this bed, I used stainless 1/2" carriage bolts.
I can answer most questions about these beds...and I have lots of pics, but not every single detail unfortunately.
1994 F150 4x2 Flareside. 5.0 w/MAF, 4R70W, stock.
1984 F150 4X2 Flareside. Mild 302 w/ 5spd. Sold.
1980 F150 4X4 Flareside. 300i6 w/ 5spd. Sold in 2021.
1980 F100 4X2 Flareside. 351w/2bbl w/NP435. Sold in 1995