DaveInDenver
Middle Income Semi-Redneck
The F150 first received a fully boxed frame in 2004. It was also when they started using hydroforming to make part of the frames, which isn't possible with an open profile or anything with a lot of voids. To be honest I think the marketing of fully boxed frames is a way of selling it as better when in fact it's just about being easier to manufacture. Back when the Toyota trucks we got pre-1995 were fully boxed they were stamping two halves and welding them, so that really was a design decision as a way to stiffen and strengthen with thinner material (the reason for boxing any frame really). I dunno what the current production technique Toyota uses for the Hilux but the Tacoma frame on mine appears still built with a welded seam on the boxed section and has a double wall through the 'C' profile back to the roughly above the rear axle. I think the rust issues of the 95-04 Tacoma (which was open only over the rear axle) probably had something to do with the current design.Pretty sure the f150 wasn't boxed until the 2000 something.
dodge didn't use a boxed frame until 2003. Chevy after that.
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