I have heard that since the 1979 F-150 Supercab has a solid front axle it is possible to do a straight swap for F250 or even F350 axles without any cutting/welding. Is this true? And if so, what years is this true on? I know that 77 and previous have narrower spring perches on the rear axle and so would require a fair bit of modification.
Am I looking for just a 78-79 f250 or can I look in the early '80s as well?

 

The cheapest way to get a 3/4 ton is to swap out a dana 60 /70 8 lug rear axle from a 78/ 79 truck as spring perches should be same width. The Dana 44 1/2 ton front axle can be converted to a 8 lug. You need to get the outer brake hub and rotors along with the larger dual piston calipers & mount brackets. 1/2 ton caliper & bracket didn't work on the 3/4 ton rotors when I mocked up 3/4 ton to a 1/2 ton axle.I'm not positive that spindle needs to be changed. You could cross reference wheel bearing for the F-150 / 250 to see if they are the same. You could swap entire front axle or brake parts from a 1976 - 79 F-250 to your axle. The only issue is the 1976-77.5 axles are disc brake low pinion where your 1979 should be a high pinion 5 lug setup.The strongest setup would be to find a 1978-79 Dana 60 8 lug that will bolt in to you truck if I recall correctly but they are rather expensive as they were only offered in 1978/78 F-250 snow fighter package or a F-350. The other issues are rear drive line for a 9" 1/2 ton would not work with a 3/4 ton Dana 60/70 rear axle. Most likely it would need to be shortened ? The Dana 60 kink pin axles from the 80's will not work with out fabrication as spring are 36" CL were 1978/79 are 31" CL. I hope this information is useful and other FTE members will chime in on what works.