I think you're right...I have a 2010 TRX4 Crew, regular trim interior with a solid rear bench. I also looked at another TRX4 before I bought mine that had the premium cloth interior, it had a split rear bench, along with the under seat cargo covers.

 

I have an 09 Laramie with leather and it has the 60-40 rear bench

 

60/40 in a 2009 bighorn cc right here!!! lol

im sure its interchangeable tho idk why it wouldnt be...cabs are the same...slight possiblity u might need brackets?

 

I have a 2010 SLT that came with a one-piece back seat and column shift. I bought a whole interior, including console, two front seats (driver power) and a 60/40 back seat that came from a 2010 crew cab a couple of months ago on eBay.

I have since then replaced the column shift with the console shift, replaced the front seats and replaced the back seat.

The back seat did not fit right away so I had to cut about two inches off rear of the floor brackets and also weld 1/4"x1/2" extensions to the hooks in the back, preventing the seat backs to flip forward when the seat bottoms were raised.

The rear seats are about 1" longer compared to the original quad cab seats, but I am overall very pleased the way it came out.

Bo

 

I have the 60/40 split as well in my 2009 slt, i guess it depends on the model/trim level u get plus people sometimes order certain packages with 100s of options available, so the parts guy is probably being lazy, mine told me that my bed wasnt 5'7" long that it was my engine liters! lol