Current developments in tractor transmission design has galloped to new heights with the introduction of CVT, Power shift, Power shuttle, hydrostatic etc besides the vastly available synchromesh and constant-mesh gearboxes. In contrary to the above existing facts of new powertrain development, there is a definite market need to revamp the heritage tractor models to be equipped with the modern transmission systems. This will help the customers have the advanced drivetrain features in these legacy tractors, that have won many hearts. One such modernization, was the development of new power shuttle transmission in legacy tractor models for TAFE tractors. Power shuttle primarily enables (a tractor in this case) to go forward and reverse by operating a wet clutch without human intervention. A flick of lever, usually on the steering column changes the direction of the tractor at the same speed of the gear selected. This research work is on the various drivetrain challenges akin to maintaining the ground speeds, base drivetrain layout, wheel base, PTO speed, etc conquered with maximum use of existing drivetrain parts. Advanced simulation tools such as KISSsoft, MASTA for new gear design and FEA through ANSYS for shafts has been used where ever necessary. A comparison was made between the legacy synchromesh transmission and new power shuttle drivetrain in order to signify the achieved results. One of such solutions, evaded a 40 mm increase of wheelbase while modernizing the heritage tractor models with that of new power shuttle transmission.