There is no doubt that 5 lugs are stronger than 4, but if you modify the motor to stress 4 lugs I'd think you should upgrade the complete suspension and then include a 5 lug upgrade.
I'd not consider it a neccessity unless your plans include mucho horsepower.
In your case, save the cash until you can upgrade the front to larger brakes and then convert the rears at the same time. You will need new rims...
There are a lot of ways to better spend your money on the suspension IMHO.
'95 Ranger 5.0 GT40X Tri-y GT40 Intake S-Trim Snow Stage 2 Lowered Baer Racing Brakes Viper Spec Tremec w/Hurst shifter Custom Interior Dakota Digital Dash Corbeau Toplines OZ Racing AM/FM/Mp3/CD/DVD/TV.
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