A new axle is in the range of $100 plus shipping in the US or at least it was a few years ago. Maybe a little less for your size.
I do not know of anyone cutting off welded on backing plates but this much I do know. If you are going to weld on the flange it has to be very square and true when welded on. At the axle factory this is no big deal. Out in the field if someone does this for a living they can set it up and do it too. But odds are high the axle has to come off so they can set it up and jig it correctly.
If the flange is not on square and true then the shoes end up being at an angle to the drum. You then end up with point contact in place of full width and they wear/burn down a whole lot faster.
Do you by any chance happen to know the run out of the drums you have now? Believe it or not, Dexter declares the drum can be up to 0.015" T.I.R. max. Only because it is a trailer drum. I also bought 4 new drums, 2 of them where under 0.005", one at 0.008" and the 3rd 0.016". The one I had the issue on the TT with was 0.024".
I only installed the 2 of them that where under 0.005".
Before buying new I went down to the local auto parts store and asked if they can turn the drum. They said they could, $19 a drum. I asked what is the run out tolerance you use? He said they will turn them to spec. I asked what is the spec? He did not know. I did not leave them with him to turn them. This was the same place that turned my prior truck disk brake rotors from me that where 0.009" out. And on disk brakes that is real bad... Never again... Ended up then buying new rotors.
If you can find a good shop, it is not a problem to turn a drum brake to within 0.005" or less. They can get it within 0.001" they just have to work at it a little. And for that skill I would expect to pay more then $19 a drum.
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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