The GTN was a very limited edition model. I believe in the region of 10-11 were made.

It was essentially a series 1.5. It arrived at the end of the Series 1 production. The Series 2 was quite a big change to allow it to go to the US market with repositioning of the petrol tank, wider cockpit, new dash, new engine/box/brakes.

https://www.classicdriver.com/en/article/morgan%E2%80%99s-aero-8-gtn-heads-le-mans

The existing 4.4L BMW engine (286bhp) was replaced with a rare Alpina 4.6L engine (330bhp and more racy cams making it even more fun). I think the gearbox may have also been changed with it.

I believe they were delivered with a removable hard top as well as the soft top. These are rare and individually matched to the car.

A general list of the changes include
- Using the standard 4.4 BMW V8 but enlarging it to 4619cc (which developed 330bhp)
- Black centre lock OZ wheels running Yoko 048 semi slick tyres
- Uprated suspension
- Side exit sports exhausts
- Carbon fibre hardtop
- Carbon fibre interior trim
- Revised lower splitter with cooling ducts for the front brakes.
- Standard colour scheme of Blue and Silver

They tend to keep a higher value than the S1/S2. Shooter and a few other members on the forum have one so if they pop up it might be best to see if they can spend some time helping you.

If you are just looking to get into Aero ownership then the S2-4 can be had for less money and offer the same (or improved depending on your taste) experience. I looked at one when I was first buying but ended up finding a rare S2 which gave me more cockpit space etc.

Everyone loves a Morgan. Even me, unless it's broken again.