So I bought the Hobbyboss Merkava IIID LIC kit and the Legends Merkava IIID update set (which is for Mengs IIID). I was amazed at how much smaller HBs stowage basket is versus the Legend replacement. It's also about 4mm narrower than the Legend resin piece. The Legend part isn't going to work without widening the rear part of the turret.

That's odd. Legend parts are usually too small for their kits. Maybe they sent a pre-production master of some sort?

It is made for the Meng kit, I believe. there are some large dimensional differences between the Meng and HB kits

But if the Hobbyboss and Meng kits are of the same tank, someone has to be off. Given their major goof on their Merkava IV's suspension, it's probably Hobbyboss.