Rangers used 2 different size gas tanks
17gal(16.5) in Regular Cab Ranger, shorter wheel base
20gal(19.5) in extended cab or Long Bed Ranger, long wheel base
Filler hoses were also different by year, one hose or two hoses
Single hose looks like this:
https://m.media-amazon.com/images/I/61PHyP5m87L.jpg
But its actually 2 hoses, smaller longer hose is where gas goes into the tank, larger outside hose is where air comes OUT while filling the tank
Your 1996 should have this kind, I think 1993 to 1997 Rangers had this type
The 2 hose filler looks like this:
https://m.media-amazon.com/images/I/61sOiEznl-L.jpg
It has a separate Vent tube, smaller tube, to let out the air as you fill the tank
So gas tanks with this type of filler would have an extra hole in the top for the Vent connection
So all gas tanks won't be the same, even if they are the same size, they will have different fittings and sizes of openings
And Step Side beds had shorter filler hoses of either type, lol
Smelling gas while you fuel up or when driving is usually cracked/broken filler vent
Can be broken EVAP system hoses, but you should have EVAP Codes come up with either of these things, they should turn on the CEL but not always
Also would set codes if gas tank itself was cracked or leaking
In anycase if you pull back or lift up the bed you should see/smell where the problem is