Help w/ 7 1/4 to 8 3/4 change over

Dhow,all the A-body rears came with 4 inch bolt pattern.To get the 4.5 bolt pattern,you,ll need to get some aftermarket axels.You can get these from Moser,Strange,Yukon.They all carry these axels,if ordering?Don,t forget to mention the size of brakes you,ll be useing.Good luck.