Are there more than the main one that is bolted on the inside frame on the drivers side? Mine is a 93 5.0L

 

I cannot speak to a 93 rig but I do know that on an late 86 full size, 5.0L with EFI, there are two fuel filters. The "second" filter is in the "usual" spot, under the driver's floor, attached to the inside of the frame rair. The "first" filter is tucked above the transfer case crossmember, attached to the driver's side frame rail. This one is hard to see and harder to replace.
Roger Carter

 

'93 only has the one filter along the frame rail. Earlier models had two.