55.2-59 1956 Do I need to notch?

[mr48chev]

I'm going to say yes with at least the notch like Dsraven showed . it took me a minute to figure that the brackets on the sides of the frame rails are for bags or coil springs. The notch over the axle and the boxing plates are what you are looking at. other than that it all depends on how low you plan to go and how much clearance you are comfortable with, You may have to have a raised notch over the axle if you intend to be real low but maybe not as much as the lay frame brigade.

The best I can offer is set your lower A frames level (most likely without springs installed. set the front static height at what you intend for it to be. then block the rear of the frame up at the height you intend to have it sit static at and start measuring.

If you don't have the tires or rollers that size that you intend to run you can use this calculator to figure out what the diameter of the tire is https://tiresize.com/calculator/ Then half the diameter plus half the axle tube diameter gives you the alleged top of your axle tube at static height. That will tell you where the axle is going to be in rellation to the frame rails.

Then you have to decide how much clearance between the frame rail and axle is "safe clearance" as there is no carved in stone measurement on that. All I can say on that is that not enough clearance means that the axle may and most likely will hit the frame rail at times.

I'm not intending to suspend my 48 on bags but plan to run a pair of bags as load leveling bags controlled by a level switch that was used on a lot of Cadillacs over the years with air shocks. That way static height will always be the same in theory.