2, in the front only. The rear has leaf springs.
Yes.
on a 91 blazer s10 4wd
I belive you have the 2.5 in that case the coil is mounted on the bottom of the intake manifold above but rear of the oil filter
No.
91 miles
I would recommend checking your distributor or coil packs depending on what you have.Plug wires and plugs.
any first gen s10 0r blazer or bervada grills will fit
Yes
8-10 psi
No.
Yes, you can swap the front coil springs from a 1991 D150 with those from a 1991 D250, as they are generally compatible due to similar suspension designs. However, the D250 springs may be stiffer and provide a higher ride height due to the heavier load capacity of the D250. It's essential to ensure that the spring dimensions and mounting points match, and consider alignment and ride quality after the swap. Always consult a service manual or a professional for specific guidance.
91