IDF From Sinai Gray To Olive Drab

So how did the changeover take place?

If by OD you mean the color used today, then the change occured in the late '70s. The original color was more greyish though than the greenish-brownish shade used today, which was adopted in the early '90s.

The IDF experimented with a three tone camo tested on Merkava Mk.2s of the 77th Battalion in the late '80s - early '90s, but the project was eventually dropped.