what happened to all the old UPS vans?

[Dab of oppo]

Just on the search for a biggish van in decent condition, this got me to thinking that UPS vans are normally quite presentable as working vehicles go.
Now the van I was thinking of was specific to UPS with a big bulbous front, sliding drivers door etc and if I remember correctly Mercedes or Iveco underpinnings.
Does anybody know what happened to all of these vans as I have never seen one other than being used by UPS, whereas other large couriers ex fleet vehicles are all over the place!

[Dab of oppo]

Thanks for the info! I didn't realise I'd get so much feedback with so much information!