Hi...
I need a cap for my '97 SR5 extended cab T100. I am hoping to buy a used one (I'm in Maine, just in case anyone has one for sale

) but I don't know the technicalities of measuring for a cap. If I measure from the outside of the rail to the outside of the rail, the bed measures 68" x 78"... is this the cap size I should be looking for?
Thanks for your help.
Steph