Conquest/Starion Springs 

This is 1888 factory info

Springs for the rear of SHP (KYB) struts are different, also the strut rod diameter of the SHP rear strut is 30mm. The standard rear strut (Tokico) rod diameter is 32mm. All front (KYB) rod diameters are 30mm.

Front
Travel, full jounce 85mm/full rebound 75mm
Spring size (coil design height & id., bar length x dia.) 346x117.2x2650x12.8
SHP 327x117.2x2485x12.8
Spring Rate [N/mm, (in lb)] 23.5 (134.4)
SHP 26.0 (148.4)
Rate at Wheel [N/mm {in lb)] 22.0 (125.6)
SHP 24.3 (138.7)

Rear
Travel, full jounce 95mm/full rebound 90mm
SHP jounce 85, travel 95
Spring size (coil design height & id., bar length x dia.) 327.7x107.8x2515x12.2
SHP 320.4x108x2385x12.0
Spring Rate [N/mm, (in lb)] 22.6 (129.5)
Rate at Wheel [N/mm {in lb)] 20.0 (114.6)


If I understand those numbers, basically the SHP front spring is shorter and the rear SHP spring since it was also a different manufacturer is also shorter but a larger overall diameter but from a smaller diameter stock and keeping with how they only made the front SHP shorter that must be the same thing for the rear just the different mfg. for the strut also needed a different diameter part to fit their perch. Being shorter changes the rate.

Combine above with this ...

PER 1989
rear springs
MB110936 w/std. up to 12/1/88
MB110935 w/H.D. up to 12/1/88
MB110937 w/std. OR H.D. after 12/1/88

std 12.2x132.2x335.2 ( 1 lt blue band ) [oil strut]
optional 12.2x132.2x335.2 ( 1 lt blue band ) [gas strut]

front springs
MB430982 std. up to 9/1/88
MB175702 w/H.D. up to 9/1/88
MB633946 w/std. after 9/1/88
MB175703 w/H.D. after 9/1/88
MB175704 w/sport susp. after 9/1/88

std 12.8x142.8x346 [oil strut]
optional 12.8x142.8x327 [gas strut]


PER 1987/88
rear springs
MB110935 w/o intercooler
MB110936 w/intercooler

std 12.2x132.2x327.7 ( 2 pink bands) [oil strut]
optional 12.0x132.0x320.4 (1 pink band) [gas strut]

front springs
MB430982 std. w/o intercooler 1987
MB430983 w/intercooler 1987-88
MB175702 w/intercooler w/handling pkg.

std 12.8x142.8x346 [oil strut]
optional 12.5x142.8x327 [gas strut]

PER 1985/86
rear springs
MB110935

12.2x132.2x327.7 (2 pink bands) [oil strut]
12.2x132.2x327.7 (2 pink bands) [oil strut]
12.0x132.0x320.4 (1 pink band) [gas strut]

*******
Now there are different 5 different rear strut sets available:
Std. susp 1985
H.D. susp. 1985
Lt. w/o intercooler 1986
Lt. std. w/ intercooler 1986
Lt. Gas w/intercooler 1986
*******
and it just gets better public/style_emoticons/default/smile.gif
front springs
MB175700 12.5x130x309-6.25 H series
MB175701 12.5x130x309-2.65 P series up to Dec. of 84
MB175702 (after Dec. of 84) 1985
MB175701 w/o intercooler 1986
MB175702 std. w/intercooler 1986
MB175702 gas w/intercooler 1986

12.8x142.8x339 ( 1 pink band, 1 blue band ) [oil strut]
12.8x142.8x346 ( 1 pink band, 1 green band ) [oil strut]
12.8x142.8x327 ( 1 green band, 1 blue band ) [gas strut]
1985
12.5x142.5x309 (1 blue band, 1 lt blue band) [gas strut]
12.8x142.8x320 (1 green band, 1 orange band) [gas strut]

PER 1984
rear springs
MB110935

12.8x132.0x320.4 (pink band) [gas strut]

front springs
MB175700 12.5x130x390-2.65 H series
MB175701 12.5x130x309-2.65 P series

12.5x142.5x309 (1 blue band, 1 lt blue band) [gas strut]
12.8x142.8x320 (1 green band, 1 orange band) [gas strut]


PER 1984
rear springs
( I didn't look at the 83 parts fiche I'll do that later[but I never did], all the other years info is from the same parts CD the dealer uses)
12.8x142.8x334 (pink band) [gas strut]

front springs
12.5x142.5x309 (1 green band, 1 blue band) [gas strut]


You need to measure the springs too
[ wire dia x O.D. x free length ]

To say that SHP springs were softer is incorrect, they were using some springs in the beginning for SHP cars that came out sometime in 1985 models

So know you are asking what is an H or P series aren't you? Must have to do with the wheel/strut/spring packages