I have a 1999 extended cab 4wd ranger that needs a new bed, I currently have a style side bed what years will i be able to swap beds with

 

Welcome to the forum

1993 thru 2011 for non-stepside

But you will need to swap over your taillights and wiring if bed is 2000-2011
1993 thru 1999 is plug and play

1993-1999 use 3-wire tail light system, they have a separate turn signal bulbs on each side
2000 and up use 2-wire, brake and turn are combined on each side
Lense sizes are the same, but wiring in the bed is different, extra wires

And 1993-1999 may also have 3 to 2 wire converter as part of the wiring, if you have a 4 pin trailer light hook up, most trailers used 2 wire

Not that it matters but around 2007 Ford added 2 more bed bolts, original 6 bolts are in the same places, but they added 2 more in different places