Does your truck have a second alternator? Might be the difference. I've got the same year and I've only got one alternator. Might be something to check and if it's bad it would kill the upper alternator in no time. Some of these trucks were intended to become service vehicles. (ambulance, telephone truck, tow trucks, etc)
Short plastic is just snapped in. Easy to break thou. If you break Tousley's got 'em for $36. ( I know)
I tilted my alternator when I removed for EGR delete. Very doable. Suggest a pair of these babies. 16" Solid Steel Pry Bar Fits the bolt hole nicely and good leverage.
Also there is a "kickstand" under the idler pulley. You release tension on the pulley the push kickstand into place. Leaves belt slack.
https://www.ford-trucks.com/forums/8...-change-3.html
See post #31.

Good Luck