I posted the following in the Towing forum also:

We have a 2003 V6 Explorer XLT 4x4 that was purchased new without the towing package, so we're limited to a maximum towing rating of 3500lbs. We want to buy a camper and don't want our choices limited by the low tow rating. I noticed the OEM towing package only added a transmission cooler, 3.73 LS rear differential, and an integral Class III hitch/bumper to the Explorer. Is it possible to add these components to the Exlorer from a junkyard or an off-road customizing shop and if so, roughly how much will it cost me? If it's not something cost-effective, I may just trade in my 2002 Maxima for a new Suburban or wait a couple years and trade the Explorer before buying a camper. Thanks for any replies.

 

You can add them, if you can find an 03 in the junkyard. You can find the tranny cooler, and the hitch aftermarket, but I am not sure about the 3.73. I would also add an engine oil cooler.

 

You can take this with a grain of salt.... but how much weight were you planning on pulling? Anything more then 3500 and I would get a different vehicle. I have not yet towed with my 99, but from everything that I have read, any weight over the 3500 and you will have problems when you get up on the hightway. The 4.0 is a stong motor, but not ideal for towing. The real question is, what rear end do you have in your Explorer? There should be a tag attached to the read diff cover that has some numbers on it. If it reads "3 L 73" you have the 3.73 Limited Slip. As for adding a hitch... just go to UHaul and they can install a ClassIII hitch for you.