ported box in a truck for type s 10

I have recently put my stereo system in to my old truck (77 Ford) because we trade my 99 Isuzu Rodeo for my wife a new car. Anyway the sub even when it was in the Rodeo was in a truck style box. Well it sounded good in the Rodeo. In the Rodeo I had the sub bridged on the rear two channels of a 4 channel amp. Well I decided when I put the system in the truck I wanted a dedicated Sub amp. I bought a PPI amp for this purpose. Well in the truck sub is loud but the bass is different, it's not boomy really, it's more bew bew, I don't exactly how to describe it hopefully ya'll understand what I mean. Anyway I like it better boomy sounding and I think the issue may be because the seat is right in front of the sub? It was suggested that I try a ported box. I haven't had a ported box in along time and never in a truck. Sorry for all the back story, but with all that said, does anybody know what size box and port would be best to put this 2003 model Alpine Type S 10" sub in to fit behind the seat of a fullsize 77 Ford truck? Thanks,

You need 1.2 Cu Ft for the box. The Vent should be 10 x 1 x 14. Edit: I got these number from Here This is the owners manual for the SWS-1043D DVC sub. I am not sure exactly what you have but this is what they are currently making.