Chad;
Just to be accurate, there are several "major changes" that have been made to that TM.
That model is probably ~ 6-7 years old.
To restore the vac level & improve heat output, I would
1. Check the max vac level with the inlet sealed.
It should be @ 16" hg.
2. Check the vac gasket on the lid above the filter.
3. Reinstall the exhaust wrap on the left exhaust manifold.
4. Increase the blower outlet where it has been changed to 2" barbs.
Also, the regulator on the pump needs to be in it's original vertical position, for proper lubrication.
It would also be easier to adjust pressure in that position.
The main restriction I see is the exhaust piping out of the HX.
I would increase it to 2.5 stainless tubing.
Lyon can contact us for a service manual with some more details.
This is a proper installation for maximising space in the GM van:
Larry