Originally Posted by Jan06xB

This is second gen with more HP and the tranny should be able to handle a little deceleration without breaking apart since engine braking puts no where near the load on the gears as acceleration does.

Originally Posted by TrevorS

The question isn't referring to allowing the engine to provide braking when in first gear, but rather, deliberately downshifting into first for the purpose of using engine braking. If more braking is needed while in second, then apply the service brakes. Shifting down to first for engine braking isn't normally a good practice for either automatic or manual transmissions. You can't even expect to have the necessary gear synchronization to support that shift. It's just not a normal design intent for first gear.

PS. The true purpose of down shifting for engine braking is to protect against service brake heating, which can result in fading and possibly brake failure. It takes very little additional brake to augment second gear (no overheat risk), and so there's no practical advantage to selecting first gear for engine braking -- and so the design doesn't typically support it.