you'll need at least 910 springs in the heads for a jake brake
Between me and a friend we've ran about 3 sets of Bosch on manual control only. 5 seconds. Only issue we ever had was when someone accidentally held mine for about 20-30 seconds

. Killed all 8 but they all came out just fine, no warp-age. Second set lasted me a season before I swapped to Berus to try them out. The Bosch were still working and came out just fine, all 8 are spares in glove box. Friends set lasted 2 seasons so far. I usually tighten them a little harder than that, with no ill effects yet. Mostly don't want to see one come flying through the hood if it vibrated out!
Its funny in some other diesel applications people consider bosch good but with the 6.9/7.3 crowd they don't like em cause the controller will burn them out in a month give or take. It overglows them a ton - like I said 5-7 seconds is plenty. The controller usually goes longer then that, and then when cold the controller will afterglow them - if you use the glowplug controller DO NOT USE bosch. It WILL kill them. Use only Beru, its the only glowplug that can take the abuse
When I bought my truck it had some champions, autolites, and who knows whats. I guess I got real lucky because all 8 came right out. Didn't even grease it up