4in vs 4.5in bolt circle rear axle

Bolt circle and stud size makes a lot more difference in trucks. That being said, if you are concerned about all out strength, you have the option of upgrading to a given size with an aftermarket axle (flange diameter matters, too, there has to be a certain amount of material outside of the stud). You could have axles made to use later truck drums with 5.5 on 5.5 bolt pattern if you’re staying with drum brakes. New drums are available in 10 & 11 inch sizes.