Something in the TOW/HOT/Swingfire category.
Excellent
"Olifantization" of Vickers MBT Mk.II is a go
Could Swingfire be refitted with warhead from Spike-ER though? Or would Spike-ER's warhead be too big? Or is Swingfire's warhead better than I think?
If the warhead is heavier on the Spike than the existing warhead on the Swingfire, you'll find all sorts of aerodynamic problems with it, including perhaps most significantly, decreased range. The Swingfire's warhead was perfectly adequate when introduced but wasn't updated as the threat changed.
I wonder why no one has mentioned Malkara. While it was big and a bit clumsy, it did have a 26lb HESH warhead. Enough to make the day of the crew of any AFV it managed to hit rather short. Interestingly, it was developed into a SAM the Seacat/Tigercat.