I would strongly suggest (assuming you havent already got the w56 transmission) to use the L52HD Marlin sells. you get the strength of the w56 in the length of the stock transmission giving you much better driveline angles in the rear.
I just about never use 5th gear with my 35's the engine runs cooler when running at 3600 rpm in 4th than 3100 in 5th (approx same speed+/- ) and I dont have to downshift at every bump in the highway.
