I have a 05 ranger 2wd 2.3l fleet truck with a 19.5 gallon tank and my new ranger only has a 16 can I swap the tanks ? My new one is. 2001 4x4 4.0l

 

Is one of the trucks a long bed and one a short bed or maybe a std cab vs an ext cab ?

Standard Cab Sort Bed Ranger have smaller tank because of the WB the longer WB Truck have the larger tanks.

I have not attempted to fit one in my 2003 to see if things go together but you if you do post up what you find, I for one would be interested.
I have tried it in my 1988 std cab short bed, when I had it and the larger Ranger Tank was too long.
There was an after market tank at the time but too much money, a five gallon can in the bed was cheaper.

 

Long bed standard cab vs extended cab short bed

 

Really it is the std cab short bed vs the rest of the configurations.

I think the Ext Cab short beds and the std cab long bed are close to the same thing in the frame/tank area.

Look at the space, look at some of the other available plastic tanks out there and start comparing.

I haven’t had enough experience with gas tanks before so I can’t help but I was looking at a tank for the rear of the frame to replace the spare tire, an aux tank, it would require a second fill and electric off/on select valve.

Sorry I can’t help more, start measuring and comparing.