Has anyone done or seen it done? is it as easy as the afh swap? any info would help :)

More info on the car in question would help.

89 mk2 breaddy :)

I have a good look at it and it wouldn't be at all easy. To the extent that if you wanted a 1.4TDI early Polo, the Ford/Peugeot HDI would probably be easier (and still by no means at all easy).

If you want economy, fit a 1.3 MH (carb) or 3F (GT) with an 8P gearbox and you should top 45mpg. If you want mental economy, do the same but with LPG.