Rick,
I think you do not need to calculate these PDF by hand.
PROC UNIVARIATE already offer these data, just save it and plot it ?
Here is an example:

data Plates;
label Gap = 'Plate Gap (mm)';
input Gap @@;
datalines;
7.46 3.57 3.76 3.27 4.85 17.41 2.41 7.77 7.68 4.09
2.52 5.12 5.34 16.56 7.42 3.78 7.14 11.21 5.97 2.31
5.41 8.05 6.82 4.18 5.06 5.01 2.47 9.22 8.8 3.44
5.19 13.02 2.75 6.01 3.88 4.5 8.45 3.19 4.86 5.29
15.47 6.9 6.76 3.14 7.36 6.43 4.83 3.52 6.36 10.8
;

ods select none;
ods output histogram=plot;
proc univariate data=plates;
histogram gap/lognormal gamma ;
run;
ods select all;

data Overlay;
set plot;
zero=0;
label CurveLabel='Distribution';
run;
title "Histogram and Density Estimates";
proc sgplot data=Overlay;
highlow x=BinX low=zero high=BinCount / type=bar barwidth=1;
series x=CurveX y=CurveY / group=CurveLabel nomissinggroup;
yaxis min=0 offsetmin=0 grid;
xaxis values=(3 to 18 by 3) valueshint;
run;