the 'floating' sill goes about between the wheel wells, the holes in the skids should give an indication of exact location ... lots of free info on Mar-Ks website

you're asking if you can pre-assemble the wood floor and then slip it into the bed? - no, the boards "float", and are held down by the skid strips bolted to every cross sill, so without all the sills you wouldn't have an "assembly", and even if you could hold it together to slip in, you'd still have to bolt the skids to the cross sills, the rear-most one of which is usually welded in .... the whole bed can be assembled off the truck, the bolts that hold it to the frame go thru the wood so you can't have it bolted on yet anyway, block it way above the frame and install the wood, then drop it back down for final bolt in - that's the "pre-assembled bed", complete except for being bolted to the frame

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics