Im not Gerdo but. . .If it helps?
We have an Engel MT45FU1 which is the 43 qt model. We got ours two summers ago from Compact appliance,TX. There website no longer shows this model?
I "googled" Engel and found www.bigfrogmountain.com
which lists all the current models and accessories. It also lists interior and external size/s.
In our experience we're thrilled with the unit. It is by all accounts very expensive given the size, but it works exacly as described. We wouldn't hesitate to buy another should it get damaged or stolen.
We use ours every August for our annual month long trip and experience all kinds of outdoor temps. At home its plugged in, in the garage keeping beverages cold year round.
The unit operates flawlessly. At first we were concerned about the interior size (aprox 43 qts) but its 100% useable, no ice, just foodstuffs.It works and switches from 110 v to 12v without missinga beat.
On days when we know we're going to be stopped for hours, we line the unit with water bottles and crank it up to freeze. When we stop, the semifrozen water bottles keep the interior cold to keep foodstuffs from spoiling.