No, you can't directly swap a 1995 Chevy 1500 transmission into a 1985 C10. The transmissions are completely different in terms of bolt patterns, input shaft dimensions, output shaft dimensions, and overall design. The 1985 C10 likely has a much older, simpler, and mechanically different transmission (likely a TH350, TH400, or SM465). The 1995 1500 likely has a 4L60E (or possibly a 700R4 if it's a non-electronic version), which is a significantly more modern electronically controlled automatic transmission.
Even if you could somehow adapt the bolt patterns, the differences in the bellhousing, computer control (the 95 would need its own computer and wiring), and other critical components would make this swap extremely impractical and very expensive. It would be much easier and cheaper to find a suitable transmission for the 1985 C10 from the correct era.
