8 3/4 chunk question

741= 1 3/8" pinion shaft dia.... 742= 1 3/4" pinion shaft... 489= 1 7/8" tapered shaft. Difference in a typical 69 Dart...nada!!! Get it and worry about building your optimum center section after it's installed, you can do all that on the bench and swap it under the car!!! Geof