Try these from my Version 10 Database:
.SUBCKT 2N6027 1 2 3
**************************************
* Model Generated by CZ LAB *
* April 20, 2001 *
* Copyright(c) On Semiconductor *
* All Rights Reserved *
*Commercial Use or Resale Restricted *
**************************************
*Programable Unijunction Transistor
*MODEL FORMAT: PSpice
* anode gate cathode
*node: 1 2 3
Q1 2 4 3 NMOD
Q2 4 2 1 PMOD
.MODEL NMOD NPN(IS=5E-15 VAF=100 IKF=0.3 ISE=1.85E-12
+ NE=1.45 RE=0.15 RC=0.15 CJE=7E-10 TF=0.6E-8
+ CJC=2.2E-10 TR=4.76E-8 XTB=3)
.MODEL PMOD PNP(IS=2E-15 VAF=100 IKF=0.3 ISE=1.90E-12
+ NE=1.5 RE=0.15 RC=0.15 CJE=7E-10 TF=1.6E-8
+ CJC=2.2E-10 TR=5.1E-8 XTB=3)
.ENDS
.SUBCKT 2N6028 1 2 3
**************************************
* Model Generated by CZ LAB *
* April 20, 2001 *
* Copyright(c) On Semiconductor *
* All Rights Reserved *
*Commercial Use or Resale Restricted *
**************************************
*Programable Unijunction Transistor
*MODEL FORMAT: PSpice
* anode gate cathode
*node: 1 2 3
Q1 2 4 3 NMOD
Q2 4 2 1 PMOD
.MODEL NMOD NPN(IS=2E-15 VAF=100 IKF=0.3 ISE=2.5E-12
+ NE=1.6 RE=0.15 RC=0.15 CJE=7E-10 TF=0.6E-8
+ CJC=2.2E-10 TR=4.76E-8 XTB=3)
.MODEL PMOD PNP(IS=22E-15 VAF=100 IKF=0.3 ISE=1E-12
+ NE=1.7 RE=0.15 RC=0.15 CJE=7E-10 TF=1.6E-8
+ CJC=2.2E-10 TR=5.1E-8 XTB=3)
.ENDS
You might want to look to see if these components are already in your database. Look under TRANSISTORS in the database. These are the only 2 in mine.