Airliner cutoff on peterbilt

Frame rail widths are pretty standard. I stuck Airliner on my KW. I didn't use the Freightliner rails since the channel was a different height and thickness.

Best get out your measuring tape and take a few measurements. I think a lot of crossmembers have slotted holes to accomodate different rail thicknesses and insert rails.

The less splices you make the better. I'd cut the Freightliner cutoff as long as possible and then make 1 splice to add it to the Peterbilt.

I would recommend getting a good shop to do this, there's a ton of measuring and fitting to get everything true and square. I'd highly recommend putting an insert sleeve along where the 2 frames are joined. Extra support doesn't hurt.