What would be the best over all rear end for a 305 TBI? I think i have 3:73's. My cars pretty much stock for now with just an open element and the basics, and i was wondering would these gears end up hurting me more than helping me?

Thanks

 

Stock your car came with 2.73's? What makes you think you have 3.73's? The only way to tell for sure is to pull the cover and look. 3.73's with the 700R4 would be fine.

 

The owner before me told me he put in 3:73's. So the rear end is already helping me or will it begin to help once i get more HP?

 

The rear end is already helping you. 3.73's and the 700R4 are a good match. I would next try to find out if he installed a posi and if he replaced/matched the speedo gears so that your spedometer reads correctly.

 

Yeah i tested it for posi . My speedo is off by about 5-10 mph, and i think the tach is off too, cause one day while i was driving the speedo was around 90 so i was going about 80 mph and the tach was around 4500. Is that right? How do you change the speedo gears, and what do i do about the tach?

 

The tach won't be affected by the new gears. Only the speedometer will be. The tachs in these cars are far from accurate to begin with. That is another problem in itself. You can change your speedo gears so that your speedometer reads correctly. Use the search feature to find part numbers and other useful info. The speedo gears for the automatics are different than the ones for the manuals. Refer to this thread for installation procedures.

700R4 speedo gear installation