FB,

I think the larger kits used to come with tanks and spinners. My 40 size kits came with them but my Arrow 40 didn't and I think they were just removed. The 20 size kits mostly didn't come with tanks and spinners (at least the two kits I've seen didn't).

Nonetheless, MK formers are basically cut to accommodate their own tanks which as you point out are mostly oval shaped. Some of these tanks should still be obtainable in Singapore and presumably in Japan. I believe that Zubba enlarged his Curare 20 formers to allow a Sullivan cylindrical 6 oz tank to fit. I imagine a similar modification might be doable for an 8 oz tank on the Mattlas 40 (nice find by the way!)

MK designs tended to use smaller tanks compared to what I'm used to installing (1-2 oz less on the 40's and 2-3 oz less on the 60's). The 20's were mostly designed for 5 oz tanks (150cc) but we have none here. The Aurora 25 was the exception which used a 6.5 oz (190cc) tank.

Hope that helps.

Building her this winter?

David.

Wow! At 53" that's a pretty short span for a 40!