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I would say Yes. There's still enough translated over form the old TMNT & OS and After The Bomb 1 to make it a good updated read. There's plenty of teaser-info (like, just what is going on in Antartica? Nobody knows...) and it gives an excellent 'moderizing' of the milleu (genetic engineering, instead of nukes, were the source of the Big Death/Crash) but still gives us fans of the original the tasty nuggets we love, like the adventures about the Gun Bunnies & the expedition into Boars-Town.

Only the ATB main book has been updated to a second edition. All of the ATB sourcebooks are still first edition, although there is little difficulty in using them with ATB2.

The TMNT books are no longer in print, and with two exceptions, their material has not been reprinted in any other books.

HU2's Mutant Animal rules seem to have been adapted from Revised TMNT and TMNT Adventures, and do not incorporate any of the changes made in ATB2.

Check Ebay. I've included some links.
Or check the Classifieds on these boards.

Mutants Down Under & Road Hogs are NOT the same, although they do seem that way.

MDU has rules for Austrailian & regional mutantions, mutant insect mounts, airship rules, some new psionics & info about Jakarta.

Road Hogs expands the original ATB1 with vehicle rules (pre-HU2 update) & introdues the Road Hogs, a pre-Big Death biker group that grew into a bandit threat. The adventure in it is a great way to introduce your players into the worlds of ATB.

TMNT Guide to the Universe expands into the TMNT Universe with stats on several Mirage properties which I will not name here, but the adventure with Doc Feral is an excellent addition to the Doc Feral saga.

Transdimensional TMNT goes even further, expanding it with
Temporal Magic, travel to alternate times & dimensions and a interesting Doc Feral adventure.

It's not in the Catalog online, so your best bets are either in the Classifieds here or click on the Ebay links I posted.