TaliaDPerkins
Senior Member
I believe nearly all frames made in the last 40 years or as are indeed heat treated.
My Ford has a double frame service manual says it is If I remember correctly. I did indeed weld on it. In fact I lengthened it about 5 feet.
(All of my added length and weld was behind the rear axle.)
Fact is these frames are designed and built to twist.
This is why the OEMs are quite serious about “no drilling holes on Flanges”
Are you of the opinion that as long as only:
* the middle third of the vertical web of a frame rail, not a flange or top or bottom third of the vertical area, is drilled through,
* and with a hole for no more than a 1/2" bolt
* and no bolt holes closer than 2" from each other
* and ideally only on the forward and rear ends of rails away from the axles
* definitely never on top of or within a foot or so of suspension attachments
That with those criteria respected a hitch or other hardware can generally be safely mounted as long as the holding power of the bolts (Grade 8 or better throughout) involved with a safety factor of like 4 is maintained?