During my enquiries I have found that to fit air suspension to a tag Hobby older than 2006 is only done by the company Dunlop, which doesn’t warrant the costs. The brake drums are in the way for the other specialist companies. (So I have been told).
I have replaced the rear suspension units (Four) for £70 a pair and as we suspected it didn’t make any difference to the height. However after 18 years I felt it was money well spent. After 18 years of use, I had to use all my muscle power and heat to remove the bolts. (Who needs to join a gym!).
Keep smiling TC