1986 3/4t rearend in a 1969 question?

[into69z]

I have a 1969 c-20. I have changed engines to a 468 bb, rebuilt the trans and now I have replaced the rearend with a 14 bolt semi-floating unit from an 86 truck. I chose this rearend because of the 3.23 ratio. I was told that I should have put the 14 bolt full floater as it is stronger than the one I installed. I could not get the gear ratio in the full floater as I was told a 3.54 was the highest gear available. I have two questions: if anyone is running the semi-floating rearend, do you haul heavy loads or tow with it and have you had any trouble? As luck will have it, I now need to go thru this rearend and install new seals and bearings-also think I may have a bent axel flange-any info on best place to get parts or anyone had simular problems?....thanks