I'm currently using R4 myself, not seeing any issue with any textures (I don't have optifine, it's way too buggy) just adding MFR now
Edit: No issue with texture on the harvester, maybe a fresh copy of the texture pack may fix?
Here we go, I took a couple screenshots. :/ And re-downloading doesn't help. This is FTB Unleashed. I haven't added anything to it.
http://imgur.com/a/Jim6W
Edit: Also, I turned NEI Highlights on to show that it is indeed a Harvester. The problem persists even with it turned off.
Edit2: So... I just logged in to play some more, and the issue is gone. That... was really really weird. I've restarted FTB around 4-5 times now, and it just raaandomly fixes itself.