difference between bellhousing

[Sirsmiley9]

For a small block bellhousing what is the difference between a 74 and 75-80 bellhousings. I have a 76 and need a bellhousing for a new small block going in, but I cant find that 75-80 bellhousing. If I get an earlier bellhousing will it still fit or will the drivetrain not go far enough or be to long

 

[Dan Brewer]

For a small block bellhousing what is the difference between a 74 and 75-80 bellhousings. I have a 76 and need a bellhousing for a new small block going in, but I cant find that 75-80 bellhousing. If I get an earlier bellhousing will it still fit or will the drivetrain not go far enough or be to long

74 bell would be 4.354" retainer register, 75 and newer 5.125 for the overdrive box.