[elhigh]

I've been engaging the clutch at about 25mph in top gear. A little testing around town - I live in a really small town with 20mph speed limits - shows that my truck will putter along at idle in top gear on the flat at about 20mph, so letting the clutch out on 5th at 20-25 turns the engine at or just above idle speed, pretty low-stress. Passengers never notice. If I'm heading down a longish hill, I'll ride it with the engine turning but the ignition off to top up the brake vacuum booster, or to keep coolant circulating. No blown heads yet and I've been doing this engine-off thing for a long, long time. I reckon it'll be okay.

My truck's at ~185,000 on the original clutch, so if it fries at this point I'm still ahead of the clutch curve.