I have 2 5th wheel trailers, a Starcraft 28' that is sold but not picked up yet & a Jayco 30'. The Jayco has a extension box for the pin and the Starcraft does not. I would like to swap the two pin boxes since the guy buying the Starcraft has a short bed pickup which needs the extended pin box. I have a long bed Dodge and do not need it.
The pin boxes are made by the same manufacturer (Leland), are the same size, and have the same bolt pattern.
Is there any additional strain on the pin box when using the extension? Does the trailer have to be made specially to handle the extended box?

 

That's a good question. ???
I can tell you that I had a 26' Nomad that the original owner installed an extended pin-box in order to pull it with a short bed F-150. It was about 7" longer than the stock one. I have also heard of RV dealers installing the extended pin boxes for folks with short-bed trucks. Even the stock pin-box on our 02 Cougar sticks out, giving it the same appearance as an extended pin-box, however I haven't seen a Cougar with a shorter one.
I would think that contacting the manufacturer of the 5ers and even the maker of the pin-box may shed some light on the subject. This is probably going to be one of those questions that have many opinions and not many facts, but I would think that the RV manufacturer recommendations would be the one to adhere to.

 

There are tales of structural failure on fivers using extended pin boxes on the RV sites. It allows more strain due to the additional length of the lever, the long box. It is best to contact the trailer manufacturer (as stated) to clear it with them. Avion was having real problems back a couple years with theirs.