Zsolt, it was worth the wait. Great finish and you pulled off what you wanted to depict nicely.
Nathan, glad you liked it. The Griffin sets do add a lot, especially the correct sized rear stowage boxes, but I will warn you the ammo compartment is very fiddly. You need to insert rounds in the tubes so you can use the point of the round to hold the rear perforated panel in the right place when fixing it to the rest of the frame. It also means you can align the tubes correctly - don't fix the tubes to the frame until you have them aligned and fix the low run, then the middle and finally the top runs. The slightest misalignment will cause you grief later. Also solder the retaining clips for the rounds to the tubes before doing anything else. Glue will not hold them and they will be easy to break off if you don't.
Do not paint the part of the round that is hidden in the tube. Any paint will make them too thick to fit. I had to scrape the paint off mine.
Good luck with your build if you go that way.
Stephen, a pity you couldn't join in. Maybe the Otter can be your entry in the APC/AFV build later this year?
I have built the IBG 1/35th scale Otter; a few accuracy issues around the doors and the driver hinged visor panel being too long and the fenders a smidgen too short in vertical height (and 1/48 scale pioneer tools!) The mortar tube is the post war truncated cone Dutch version, not a straight tube. With some TLC it comes out quite well. Not sure if the 1/72nd scale has the same issues around the doors and visor but the difference in the fender would unlikely be noticeable.
For my build I just sliced out a section of the door, repositioned the hinges and added a strip in the bottom of the door opening to raise them to the right height. Same for the visor: