Your lack of fluid has likely wrecked a bearing or two. I test drove a 79 F150 4x4 back in 85, it was making similar noises in 3rd (granny gear 4 spd.), I told the dealer I'd take it if they would fix the tranny. They quickly fixed it and it was a great truck, and served me well for 80,000 + miles (had right at 100,000 when I bought it). A competent independent shop should be able to handle it without breaking the bank.