1965 was the first year for the slip yolk on an auto trans. Manual still had ball & trunnion in 65.
You are fine as long as the driveshaft angles are correct. Hemi drag cars back in the day made more torque and power and the B & T driveshafts were fine.
Everything is stock so the angles should be fine. I threw on a kit from Brewer’s.
One word of caution on the B&T. Make sure you don’t over grease the unit on a drag car. I have seen a few boots burst from grease settling in the boot over time then at very high speeds - 120 +, the centrifugal force rips the boot. This was back in the late 60’s, maybe the new boots are thicker.
If the boots are rubber, I don't trust anything rubber these days longevity wise.Suspension bushings as an example, I've seen new brand name ones start to fail in fiver years or less. Even some of the hoses seem to age pretty quickly. As far as the B+T, they'll take the abuse no problem.
Myself, I'd vote for conversion of some sort
